Bowflex
Bowflex SelectTech 840 Adjustable Kettlebell (8–40 lb)
LiftEvidence pick: Best Adjustable Kettlebell
One dial replaces six bells from 8 to 40 lb
- Best for
- Small rooms and general fitness training that uses several light-to-moderate bells.
- Skip if
- Heavy swings beyond 40 lb, or ballistic work where a compact solid bell sits better on the forearm.
- For less
- Amazon Basics Kettlebell (budget) — The cheapest solid cast-iron bell with an enormous review base
Bowflex
Adjustable
8, 12, 20, 25, 35, 40 lb
Amazon customer rating
4.8/5 from 6,168 ratings
Checked October 7, 2026
- Type
- Adjustable
- Weights available
- 8, 12, 20, 25, 35, 40 lb
- LiftEvidence score
- 7.7 / 10
- Price band
- Mid-range
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Quick verdict
LiftEvidence editorial assessment
An adjustable kettlebell that changes between 8, 12, 20, 25, 35 and 40 lb with a dial, replacing six bells in one footprint. Owners rate the quality, easy adjustment and value against buying six bells. It tops out at 40 lb, and its larger plastic-shrouded body is less suited to high-rep snatches and cleans than a solid bell.
Specifications
Source: manufacturer listing
As stated by the manufacturer (website or Amazon listing; conflicts are noted). Information that was not available or could not be confirmed is omitted or marked “Not reliably published”.
- Brand
- Bowflex
- Model
- SelectTech 840
- ASIN
- B07X64MXBS
- Type
- Adjustable
- Weights available
- 8, 12, 20, 25, 35, 40 lb
- Sold as
- Single adjustable bell
- Adjustment
- Dial; six settings
Sources: Amazon.com listing. Checked October 7, 2026.
Who it suits
LiftEvidence editorial assessment
Best suited to
- Small Spaces
- General Strength
- Beginner
Small rooms and general fitness training that uses several light-to-moderate bells.
Less suitable for
Heavy swings beyond 40 lb, or ballistic work where a compact solid bell sits better on the forearm.
Strengths and drawbacks
LiftEvidence editorial assessment
Strengths
- Six weights in one bell
- Fast dial adjustment
- Huge review base (6,168)
- Saves floor space
Drawbacks
- Maximum 40 lb
- Bulkier body than a solid bell
- Plastic components
- App membership promoted, not required
Handle, use and durability
LiftEvidence editorial assessment
Our interpretation of the specifications, stated construction and recurring customer feedback. We have not independently tested this product.
- Handle comfort
- Good
- Swings, cleans and snatches
- Moderate
- Finish durability
- Good
- Consistency across weights
- Good
- Build quality
- Good
- Durability
- Good
Evidence and product claims
Scientific evidence, independent testing and manufacturer claims are different kinds of information and are not equivalent.
Independent testing
No independent laboratory testing of this model identified.
Manufacturer claims
Replaces up to six kettlebells; includes a JRNY app trial (manufacturer listing).
Marketing statements; not independently verified.
Customer feedback
Source: Amazon customer reviews · checked October 7, 2026
Amazon customer rating
4.8/5 from 6,168 ratings
Checked October 7, 2026
Customer ratings reflect user experience on Amazon. They are not LiftEvidence ratings and are not controlled evidence.
Recurring themes
Owners rate the quality and how easily it switches between 8 and 40 lb, consider it well worth the money compared with six separate bells, and value the space it saves. The grip is comfortable, though some note drawbacks with the handle.
Commonly praised
- Easy adjustment
- Space saving
- Value
Commonly criticised
- Some handle complaints
Editorial scores
LiftEvidence editorial assessment · 0–10
7.7/ 10 · LiftEvidence score (weighted)
- Handle quality · 20%
- 7.0
- Build & finish · 20%
- 7.0
- Accuracy & consistency · 15%
- 7.5
- Versatility · 15%
- 8.0
- Specification transparency · 10%
- 8.0
- Owner feedback · 10%
- 9.0
- Value · 10%
- 8.5
Editorial judgements from the manufacturer's specifications, stated construction and recurring customer-review themes, using the same criteria for every product in this category. They are not measurements, and we have not tested this product. How we evaluate
Compare with other kettlebells
- REP Cast Iron Kettlebell
Cast iron · 1–32 kg (16 kg reviewed)
- Titan Competition Kettlebell
Competition (steel) · Range of competition weights (16 kg reviewed)
- Lifeline Kettlebell
Cast iron · Multiple weights (24 kg reviewed)
- Amazon Basics Kettlebell
Cast iron · Many pound weights (25 lb reviewed)
- Bells of Steel Adjustable KB
Adjustable · 12–20.5 kg (18 settings)
- REP Adjustable Kettlebell
Adjustable · 40 lb model reviewed (heavier versions sold)
- Yes4All Powder Coated
Cast iron · 9–88 lb (listing default: 22 lb)
Where to check the price
LiftEvidence is not the seller. These links lead to the Amazon listing for this model; availability differs by country.
Bowflex SelectTech 840
Check price on Amazon