CORE Duffel Medium 35L
Man wearing beige neutral CORE Duffel over shoulder inside gym
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Side view of beige neutral CORE Duffel with weight lifting belt attached inside sleeve
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Beige neutral CORE Duffel Internal divider organization system packed with drink bottles, wrist wraps and workout gear
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Side by side of large and medium CORE Duffel showing size difference
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CORE Duffel Medium 35L

4.8
Rated 4.8 out of 5 stars
4.8 Stars (1,244 Reviews)
$150 $170
Size: Medium 35L
Mini 15L
Mini 15L
Medium 35L
Medium 35L
Large 51L
Large 51L
Color: Natty
Black
Natty
Green
Limited Edition - Waxed Canvas:
Tan
Black
Camo
Traditional
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Duffel Divider
Duffel Divider
$50 $60
Matching Lifting Belt
Matching Lifting Belt
$50 $60
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OUR #1 GYM DUFFEL FOR WEIGHTLIFTING

  • External weightlifting belt attachment
  • 13/15” Internal laptop sleeve
  • Sealed internal shoe compartment
  • Dual bottle pockets 

Do you even lift? If so, meet your new favorite lifting partner. Say goodbye to your belt taking up precious space in your bag, with this unique and specially designed lifting belt attachment that ensures functionality isn’t compromised whatsoever. The CORE Duffel is made to store everything you need and support you every time you step into the gym.

(Lifting belt sold separately)

Covered by our guarantee to be free of defects in material or workmanship. If there is a defect in materials or workmanship KNKG will repair or replace your bag.

Our bags are meticulously designed to stand up to the test of time. We utilize durable materials, coupled with top-notch craftsmanship and rigorous testing, resulting in the toughest bags in the game. You can confidently pack your bag to its maximum capacity without worrying about it stretching or tearing.

The CORE Duffel is made from:

  • 500D nylon body material (PVC backing)
  • YKK zippers
  • Powder-coated steel buckles
  • Ripstop nylon lining
  • Nylon webbing
​
CORE DUFFEL
SIZE COMPARISON
Capacity
Bag Weight
Height (H)
Width (W)
Depth (D)
Shoe Storage
Laptop Sleeve
Lifting Belt Size
MINI
15 L / 4 GAL
0.6 kg / 1.3 lbs
23cm / 9.1"
38cm / 15"
18cm / 7.1"
Not recommended
iPad
KNKG Belt
MEDIUM
35 L / 9.2 GAL
0.8 kg / 1.8 lbs
28cm / 11"
45cm / 17.7"
28cm / 11"
Size 10
Up to 13"
6.3" (W) - 45.7" (L)
LARGE
51 L / 13.4 GAL
1 kg / 2.2 lbs
32cm / 12.6"
50.8cm / 20"
32cm / 12.6"
Size 13
Up to 15"
6.7" (W) - 51.5" (L)
Capacity
Bag Weight
Height (H)
Width (W)
Depth (D)
Shoe Storage
Laptop Sleeve
Lifting Belt Size
MINI
15 L / 3.96 GAL
0.6 kg / 1.3 lbs
23cm / 9.1"
38cm / 15"
18cm / 7.1"
Not recommended
iPad
KNKG Belt
MEDIUM
35 L / 9.2 GAL
0.8 kg / 1.8 lbs
28cm / 11"
45cm / 17.7"
28cm / 11"
Size 10
Up to 13"
6.3" (W) - 45.7" (L)
LARGE
51 L / 13.4 GAL
1 kg / 2.2 lbs
32cm / 12.6"
50.8cm / 20"
32cm / 12.6"
Size 13
Up to 15"
6.7" (W) - 51.5" (L)

Workouts are tough but these bags are tougher. Effortless to carry and palpably robust. This thing does it all and measures in at the perfect size.

Designed for serious lifters who crave serious organization.

This is the best gym bag for powerlifters. Many amazing features that set this bag apart from its rivals. The outer material is tough, durable, and lightweight while also being water resistant and easy to clean.

FAQS

The main difference is the unique weightlifting belt attachment. This feature allows the bag be used as normal, while carrying a cumbersome lifting belt on the outside. Other changes are the volume (35L) and the layout.

Most of the materials are the same as used in other KNKG bags. YKK zippers, heavy duty buckles, nylon lining and webbing are all the same. In the CORE range, we have gone for a lighter 500D nylon outside and a new velcro logo feature that allows you to go 'incognito' with your own patches.

Measure the widest point of your belt and its length.

The CORE35 (medium) duffel can fit a belt up to 6.3"/16cm wide and 45.7"/116cm long.
The CORE51 (large) duffel can fit a belt up to 6.7"/17cm wide and 45.7"/116cm long.

A lever belt can fit, but you should count the lever into your measurement.

The CORE35 (Medium) will fit size 10 shoes. The CORE51 (Large) will fit size 13 shoes. Larger shoe sizes will fit our PLUS Duffel.
4.8
Rated 4.8 out of 5 stars
Based on 1,244 reviews
98%would recommend these products
Slide 1 selected
1,244 reviews
  • JC
    Jason C.
    Verified Buyer
    Reviewing
    CORE PRO Duffel Medium 35L
    I recommend this product
    Rated 5 out of 5 stars
    Perfect Gym Bag

    I’ve gone through several gym bags, and the CORE PRO Duffel Medium 35L is easily one of the best I’ve owned. The size is perfect — big enough to carry everything I need for the gym without feeling bulky or oversized.

    One of my favorite features is the dedicated lifting belt holder. I use a 10mm leather Pioneer belt, and being able to secure it to the outside of the bag instead of stuffing it inside is a huge plus. It saves a ton of space and keeps the rest of my gear much more organized.

    There’s plenty of room for my shoes, change of clothes, water bottle, straps, accessories, and everything else I bring to train. The build quality is excellent as well — the material, zippers, handles, and overall construction all feel very durable.

    It looks great, carries comfortably, and feels like a bag that will hold up for years. If you lift seriously and carry a belt regularly, the 35L is extremely well thought out and makes you want to see what other awesome products KNKG has.

    Highly Recommend.

    Was this helpful?
  • CS
    Clayton S.
    Verified Buyer
    Reviewing
    CORE PRO Duffel Small 25L
    I recommend this product
    Rated 5 out of 5 stars
    Everything I need

    I am very happy with this purchase. It is a perfect blend of quality and classiness, and the size is just right for me. I also love the way the belt integrates with the bag. First class!!

    Was this helpful?
  • GW
    Glenn W. W.
    Verified Buyer
    Reviewing
    CORE Duffel Waxed Canvas Mini 15L
    I recommend this product
    Rated 5 out of 5 stars
    Great Gym Bag

    Received my bag a couple weeks ago, and love it. It is so well made, and the size is perfect for my gym accessories.

    Was this helpful?
  • A
    Andrew
    Reviewing
    CORE PRO Duffel Medium 35L
    I recommend this product
    Rated 5 out of 5 stars
    5 Stars

    Great quality, perfect size, quick delivery

    Was this helpful?
  • C
    Cesar
    Reviewing
    CORE Duffel Waxed Canvas Medium 35L
    I recommend this product
    Rated 5 out of 5 stars
    5 Stars

    The quality and the presentation of the duffel went far above expectations and I’m eager to see what future items I can pair this with!

    Was this helpful?
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Ultimate Gym Bag with Weightlifting Belt Attachment — KNKG CORE Duffel

Built for serious lifters, the CORE Duffel is the gym bag that solves one of the biggest packing problems: cramming your lifting belt inside your bag. With its iconic external belt attachment, this duffel keeps your belt secure on the outside, saving precious space inside for the gear that matters.

Why the Weightlifting Belt Attachment Matters

Most gym bags weren’t built for people who take their weightlifting serious. Stuffing a thick lifting belt inside a bag means less room for everything else, and more time sifting around inside your bag. The CORE Duffel changes that with an external weightlifting belt sleeve designed specifically for heavy training gear:

  • Save Space: Carry your belt outside and keep the interior free for other gear.
  • Secure Fit: Reinforced straps hold your belt firmly in place, no slipping or sagging.
  • Quick Access: Grab your belt instantly without digging through your bag mid-session.
  • Proven by Lifters: Tested by athletes who lift heavy and pack large.

What Fits Inside

The CORE Duffel isn’t an everyday commuter bag — it’s designed for the gym. The interior and compartments give you space for everything you need for training:

  • Weightlifting shoes or sneakers (dedicated shoe compartment)
  • Change of clothes
  • Shaker bottle or water bottle (dual external bottle pockets)
  • Chalk container
  • Knee sleeves, wrist wraps, straps
  • Lifting accessories (grips, straps, bands)
  • Towel
  • Headphones or gym electronics
  • Snacks or post-workout supplements
  • Phone, wallet, and keys (secure valuables pocket)

With your lifting belt attached on the outside, the CORE Duffel has more interior space to comfortably fit everything else you need for a serious training session.

Materials & Build

Like every KNKG bag, the CORE Duffel is built to take a beating. From heavy training sessions to being tossed in the trunk or dropped on the gym floor, it’s designed to last. Reinforced stitching, abrasion-resistant fabrics, and quality hardware mean this bag doesn’t just survive hard use — it thrives on it.

  • 500D nylon body material with PVC backing
  • Ripstop nylon lining
  • Heavy-duty YKK zippers
  • Reinforced nylon webbing straps and handles

Why Choose the CORE Duffel?

  • Famous and trusted external weightlifting belt attachment
  • Purpose-built for lifters — not for everyday commuters, built for gym rats who take their training seriously
  • Smart compartments: shoe storage, dual bottle pockets, valuables pocket
  • Premium materials built to handle heavy training loads
  • The gym bag that keeps your belt secure and your gear organized