The best adjustable kettlebell in the UK depends on how you want to change weight. The Bowflex SelectTech 840 offers the widest span (3.5 to 18 kg) with a dial. The PowerBlock Pro offers a 5-year warranty and a magnetic selector pin, in 8 to 16 kg or 35 to 62 lb ranges. Order follows published specification.
How does an adjustable kettlebell work?
An adjustable kettlebell is a single bell whose handle lifts out of a base or stack with only the selected weight attached. You choose a setting, lift the handle straight out, and the unselected weights stay behind. The two models with maker specifications differ in how you choose.
- Dial (Bowflex SelectTech 840). You turn an adjustment knob until the weight shows in a window. The manual describes a click at each setting and a locking mechanism that only lets the knob turn when the handle is fully inserted, and is designed to lock the handle to the bottom plate if a weight is only partly selected.
- Selector pin (PowerBlock Pro). You insert a magnetic steel pin at the setting you want, then lift the handle straight up. PowerBlock's manual warns to check the pin is fully engaged before lifting, because incomplete contact can let weights fall.
Other makers sell multi-setting kettlebells on similar ideas. Where there is no maker page with a specification, this guide does not describe them, so check the maker's own documents before buying.
What does the specification comparison show?
The Bowflex gives the most settings and the smallest starting weight, and PowerBlock gives the longer warranty and a separate heavier model. The table sets the published figures side by side.
| Model | Settings | Method | Stated dimensions | Handle | Warranty |
|---|---|---|---|---|---|
| Bowflex SelectTech 840 | Six: 3.5, 5.5, 9, 11, 16, 18 kg | Dial | 22.4 x 17.8 x 31.8 cm | Not published | 2 years on parts |
| PowerBlock Pro 18-35 lb | Four: 18, 22, 26, 35 lb (8, 10, 12, 16 kg) | Magnetic pin | 5.75 x 4.25 x 10 in (about 14.6 x 10.8 x 25.4 cm) | 32.77 mm | 5 years |
| PowerBlock Pro 35-62 lb | Four: 35, 44, 53, 62 lb | Magnetic pin | 8 x 5.5 x 11.25 in (about 20.3 x 14.0 x 28.6 cm) | 32.77 mm | 5 years |
PowerBlock publishes these in pounds and inches, so the metric dimensions are converted. The Bowflex is around £199 (checked Oct 2026). No UK price is confirmed for PowerBlock, whose maker page is a US-dollar store page, so ask a UK dealer. PowerBlock's manual says international customers should go through the authorised dealer they bought from for warranty fulfilment.
Which adjustable kettlebell suits which buyer?
The answer follows from the settings you expect to use and the warranty you want. The three cases below are reasoned from the specifications.
Wanting the widest span in one unit
The Bowflex runs from 3.5 kg to 18 kg, so one unit covers a light setting and a fairly heavy one. The steps are uneven, for example 11 kg to 16 kg, which matters if you progress in small increments. The manual's parts list shows plates of 4, 8, 5, 10 and 5 lb on an 8 lb handle, which accounts for the gaps. Read the Bowflex 840 review for more.
Wanting a longer warranty or more top-end weight
PowerBlock lists a 5-year warranty and a separate 35-62 lb model. The 18-35 lb model cannot be expanded, so if you outgrow 16 kg you would buy the larger unit rather than add to it. The steps on the 18-35 lb model are 4 lb, 4 lb, then 9 lb. See the PowerBlock review.
Wanting a very light starting weight
The Bowflex's lowest setting is 3.5 kg and PowerBlock's lowest Pro setting is 18 lb (8 kg). PowerBlock also lists a Sport model at 10 to 20 lb with a 34 mm handle, but its range page marks it sold out, so confirm availability.
What do the specifications not tell you?
Neither maker publishes everything a buyer might want to compare. Bowflex's page does not state materials, handle diameter or what is in the box. PowerBlock describes steel construction, though its pages use the terms steel shell and cast steel in different places. Neither page gives noise levels or finish. Treat any claim on those points that does not come from the maker as unverified.
Delivery and returns also differ. The Bowflex UK page lists an approximate delivery term of 28 days from order confirmation for credit card payments and a 7-day cooling-off period, and at the time of checking it showed the item as sold out. GOV.UK business guidance says customers buying at a distance can cancel up to 14 days after delivery, and that a business must offer a full refund for an item that is faulty or not as described. Check stock, the final price and the seller's terms.
What safety checks do both makers require?
Both makers require inspection before every use and say never to drop the bell. The specific points are below.
- Inspect the kettlebell before each use and do not use it with worn, damaged or loose parts.
- Never drop it. Both manuals say this can damage the bell, and both makers say it voids the warranty.
- Lift the handle straight out of the base or stack. Bowflex's manual says not to tilt it until it is clear of the unselected plates; PowerBlock's says turning the handle sideways may tip the inner weights.
- Do not use the bell to support your body weight, for example as a push-up handle, per the Bowflex manual.
- Bowflex asks you to test the locking mechanism monthly; PowerBlock asks for inspection before each use and a visual check once a week.
- Do not strike the bell against other equipment: PowerBlock says this could dislodge the pin.
Both manuals tell you to consult a physician before starting an exercise programme. For technique, ask a qualified coach. See also home gym safety tips.
What does the Bowflex locking-mechanism test involve?
It is a monthly check described step by step in the owner's manual. With the handle in the base and the knob at 8 lb (3.5 kg), you withdraw the handle and gently try to turn the knob, which should not rotate. You then reinsert the handle, turn the knob to a position between two settings, and try to lift the handle out. If the knob stays between settings, the manual says not to use the kettlebell. The manual also asks you to check the handle assembly for free play. If the lock fails any step, stop use until approved service is available.
Can I repair an adjustable kettlebell myself?
No. Both manuals say the product is not designed to be serviced by the customer and tell you to contact the maker or, for Bowflex outside the US and Canada, your local distributor. Bowflex's manual allows cleaning with a cloth lightly dampened with warm water and mild soap and says not to use solvents, harsh detergents or bleach. PowerBlock asks for a soft microfibre cloth and warm water, with no ammonia, acid-based or abrasive cleaners.
Who should skip an adjustable kettlebell?
If you know the single weight you will use, a fixed cast-iron bell has no mechanism and no ceiling set by a setting. If you want something to move between rooms, note that the Bowflex's manual lists an assembly weight of 18.4 kg including the base. To compare against a fixed option, see the best kettlebell guide or kettlebell vs dumbbell training.
