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Curved vs straight jaw locking pliers

Updated: 21 October 2026

You have a length of 22 mm steel pipe in one hand and a flat bracket in the other, and one pair of locking pliers will not hold both of them well. Curved vs straight jaw locking pliers is that fork: a curved jaw wraps a tube or a hex head, and a straight jaw meets a flat face. Length and brand come after that. The scored table is on the [grip pliers comparison](/hub/pliers/grip-pliers). The Products Compared editorial team mapped the three amazon.co.uk listings in this comparison on 19 October 2026. We did not measure jaw radius in a workshop. A qualifying purchase can earn a commission at no extra cost to you.

You have a length of 22 mm steel pipe in one hand and a flat bracket in the other, and one pair of locking pliers will not hold both of them well.

Our top picks

STANLEY Stanley FatMax locking mole grips 250 mm

Best overall

STANLEY Stanley FatMax locking mole grips 250 mm
9.0/10about £23.10
View offer
WORKPRO WORKPRO 3-piece locking pliers set

Best value

WORKPRO WORKPRO 3-piece locking pliers set
8.0/10about £21.99
View offer
Amtech Amtech 130 mm locking grip pliers

Alternative

Amtech Amtech 130 mm locking grip pliers
6.4/10about £4.95
View offer
On this page
  1. 1.What the two jaws are for
  2. 2.Which jobs need which jaw
  3. 3.What you can actually buy in this comparison
  4. 4.Jaws this page will not sell you

What the two jaws are for

A curved jaw is a shallow C. The teeth sit on a radius, so they find pipe, bar and the corners of a hex nut. Wonkee Donkee's UK types page treats curved jaws as the default for pipe, nuts and bolts. B&Q's line is simpler: these are locking pliers, so the jaw stays shut once you have chosen the shape. A straight jaw is two flat faces. It meets sheet, plate, a bracket and a square tube face. Trade copy often mentions welding and a portable vice. That is the job, not a promise that a 165 mm pair will hold a weldment square. A curve on thin plate touches at two points and marks the face. A straight jaw on pipe sits on the crown and slips when you turn. V-jaw pairs are not in this set. The buying order is on the mole grips buying guide.

Which jobs need which jaw

Pipe, round bar and a hex that still has corners want curved. A 22 mm waste pipe, a scaffold fitting, box you are treating as a tube: wrap it. A rounded head is still a curved job. Sheet, plate, a flat bracket and the face of square tube want straight. A C-clamp welding plier has a wide throat and usually a swivel pad. A straight-jaw mole grip will not give you that throat. Drilling a 3 mm mild-steel bracket, a 165 mm straight jaw sitting fully on the face stops the bracket spinning. The 250 mm curve holds it at two points and the hole walks. The same curve is the right tool on the 22 mm pipe beside it. Once the jaw is chosen, the screw-and-click sequence is on how to use mole grips.
STANLEY Stanley FatMax locking mole grips 250 mm

Testsieger

STANLEY Stanley FatMax locking mole grips 250 mm
9.0/10about £23.10
View offer

What you can actually buy in this comparison

If you only buy one pair from this set, buy the Stanley FatMax 250 mm curved. UK reviews describe a hold on pipe, box section and a strut shaft. There is no straight jaw in that box. The only straight jaw here is the WORKPRO 165 mm piece, beside 250 mm and 180 mm curved jaws. UK reviews mention a wobbly small pair and jaws that do not line up, so do not treat that straight jaw as a weld-fit-up tool. The large curved piece is the pipe and fastener jaw. The Amtech is also curved, listed at 130 mm, and too small for most pipe in a UK house. A curved pocket pair does not become a straight jaw. Who should skip each listing is on best mole grips.

Jaws this page will not sell you

Long-nose, V-jaw, parrot-nose, welding C-clamp and self-adjusting locking pliers are not in this comparison. None of the three listings is marked to BS EN IEC 60900. Jaw shape is not insulation. WORKPRO's TPR is a comfort grip on both geometries. If the nut still has flats, water-pump pliers may be the better first tool. If you need a third hand on pipe or a last-resort bite on a rounded head, stay with a curved locking jaw: Stanley 250 mm or the large WORKPRO piece. Buy the set when the straight jaw is a real second job.

Common questions

Curved or straight jaw for a first pair?
Curved, and 250 mm if you are buying from this set. That is the Stanley single, or the large piece in the WORKPRO box. A first pair in a UK garage is usually pipe, a hex nut or a third hand, all of which wrap. Add a straight jaw when you already know you clamp plate.
Which jaw for pipe?
Curved. The radius wraps the tube. A straight jaw sits on the crown and slips when you turn. In this set that is Stanley 250 mm or the WORKPRO 250 mm and 180 mm curved pieces. The Amtech is also curved, but too small for most pipe.
Which jaw for sheet or a bracket?
Straight. You want two faces on the work, not a hollow. The only straight jaw here is the WORKPRO 165 mm piece. If you only own the Stanley, you can clamp a bracket with the curve, but expect two-point contact and marks.
Can curved jaws hold a hex nut?
Yes, that is a standard curved job. The radius sits on the faces. If the nut has already rounded, it is still a curved job and a last-resort technique, not a reason to switch to straight. Do not use serrated jaws as your everyday spanner.
Does this comparison include a straight-jaw pair?
Yes, one: the 165 mm straight jaw in the WORKPRO three-piece set. Stanley and Amtech are curved only. If a straight jaw is why you are buying, that set is the listing, with the wobble notes on the small pair attached.
What about V-jaw or parrot-nose?
They are a compromise jaw on other UK catalogues. None of these three ASINs is sold as V-jaw. Do not read a curved title as a V. If you need that middle shape, you are shopping outside this comparison.
Is a C-clamp the same as a straight jaw?
No. A welding C-clamp has a deep throat and usually a swivel pad. A straight-jaw mole grip is still a plier that locks on the edge of plate. The WORKPRO 165 mm piece is the latter. It will not stand in for a C-clamp on a wide fabrication.

Related pages

Grip pliers

Best mole grips UK: top pick, set, or a pocket pair

Mole grips buying guide: jaw, length and lock first

How to use mole grips: set, lock, and then release

Mole grips for a rounded nut: last bite, then stop

Sources

Public UK sources from the research digest, last checked on 19 October 2026. Shelf prices and star lines are the amazon.co.uk figures in the display file.

  1. Stanley FatMax locking mole grips, amazon.co.uk B01MQK1HT7 (retrieved 19 October 2026)
  2. WORKPRO 3-piece locking pliers set, amazon.co.uk B01KZM2R4O (retrieved 19 October 2026)
  3. Amtech 130 mm locking grip pliers, amazon.co.uk B009DNBIKG (retrieved 19 October 2026)
  4. Wonkee Donkee Tools: which type of mole grips (retrieved 19 October 2026)
  5. HSE: PUWER overview (retrieved 19 October 2026)
  6. BSI: BS EN IEC 60900:2018 (retrieved 19 October 2026)
  7. Screwfix: pliers buying guide (retrieved 19 October 2026)
  8. B&Q: mole grips (retrieved 19 October 2026)