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Flap disc buying guide

Updated: 21 October 2026

You already own an angle grinder, and the amazon.co.uk rows for a flap disc look like the same orange circle. The decision that saves a return is whether the disc fits the guard, then whether the shape, grit and marked speed match the job you actually have. This flap disc buying guide runs those checks in that order, from the twelve listings the Products Compared editorial team compared on 19 October 2026. The [flap disc comparison](/hub/sanders/flap-discs) holds the pack-by-pack table. This page does not name a winner. Prices are the shelf prices captured that day. If you buy through our links, we may earn a commission at no extra cost to you.

You already own an angle grinder, and the amazon.co.uk rows for a flap disc look like the same orange circle.

Our top picks

Okeno Select Okeno Select flap discs

Best overall

Okeno Select Okeno Select flap discs
6.9/10about £9.99
View offer
PRETEC PRETEC flap discs

Rank 2

PRETEC PRETEC flap discs
8.4/10about £11.99
View offer
Nisorpa Nisorpa flap discs

Rank 3

Nisorpa Nisorpa flap discs
7.2/10about £32.99
View offer
On this page
  1. 1.What you are fitting to the spindle
  2. 2.Six checks before the price
  3. 3.When the title and the table disagree
  4. 4.Where the shortlist and the fitting live

What you are fitting to the spindle

A flap disc is a hub of overlapping abrasive flaps, held at an angle so they grind, blend and finish. A thin cut-off wheel slits. A thick bonded wheel, often about 6 mm, is the depressed-centre grinding disc. Those three share a spindle and then diverge, which is why the flap disc vs grinding disc page exists. Norton’s UK guide treats 115 mm as the common size, and eleven of these twelve packs are that diameter. A label that says 4.5 inch is the same guard. Gmozkrn at £12.99 is 125 mm. The bore on these rows is 22.23 mm, and the hole does not tell you the guard size. FEPA’s leaflet is blunt about the guard staying on.

Six checks before the price

Diameter first: a 115 mm guard takes a 115 mm disc. Gmozkrn at £12.99 is 125 mm Type 29, and the matching bore does not make it fit. Bore second: 22.23 mm on these rows. Confirm it when a bullet is vague. Shape third. Type 27 is flatter, about 0–15° for blending. Type 29 is conical, about 15–25° on a weld. Engweld’s UK guide uses those bands. T29 means Type 29. A profile cell that says Backing Pad, P60 or a model code has not told you the shape. The angles sit on the type 27 vs type 29 flap disc page. Grit fourth, from Engweld’s rule of thumb: about 36–40 for heavy removal, 40–60 for weld grinding, 60–80 for rust, 80–120 for a finer scratch. Grain fifth: aluminium oxide on the budget packs, zirconia on the coarse ones. Neither name is a removal rate we measured. Speed sixth: most 115 mm rows print 13,300 rpm, Nisorpa 13,700, SDLONLIGR 13,000. MIDO prints 13.3 rpm, a listing error. If the disc’s mark is below the grinder, choose another ASIN.
Okeno Select Okeno Select flap discs

Testsieger

Okeno Select Okeno Select flap discs
6.9/10about £9.99
View offer

When the title and the table disagree

A title that lists 40, 60, 80 and 120 grit is an assortment, not one finish. Anesty’s title says that mix and a 20-pack; the grit field says 120 and the pack field says 1. Merryland’s title says 20 discs and the pack field says 1. Gmozkrn’s title says a 9-pack and the pack field says 1. The live page, then the packet, settles it. PRETEC’s URL is B0CSSX6VDD and another field carried B0CSSVHYFL, so we kept the URL. Total Abrasives’ contents line says cutting discs on a flap title. SDLONLIGR has no star line and no profile. EN 13743 is not printed on any of the twelve. Price is last. On 19 October 2026 the shelves ran from £9.99 for ten 40 grit discs to £32.99 for fifty 80 grit discs, about £0.66 each. A 50-pack of the wrong grit is still the wrong grit.

Where the shortlist and the fitting live

Conditional picks, including who should skip a 5.0 from four reviews, sit on best flap discs. We compared amazon.co.uk listings and public UK guidance. We did not grind a test plate. Get a trained person for structural steel that will be inspected, for overhead work you cannot brace, and for employed work where PUWER expects abrasive-wheel training. Stainless, where the listing never names a grain, is the same kind of stop. A carton of bent flaps is a return, not a disc you run to see.

Common questions

What diameter flap disc fits my guard?
Match the disc to the guard, not only to the 22.23 mm bore. Eleven packs are 115 mm, the usual UK 4.5 inch size in Norton’s guide. Gmozkrn at £12.99 is 125 mm and does not belong under a 115 mm guard. If the labels disagree, the guard is the limit. Taking it off to make a disc fit is outside this guide.
Is 22.23 mm the standard bore on these packs?
On these twelve rows the bore is 22.23 mm. The hole only tells you the disc can slide on. It does not tell you the diameter, the type or the speed. Confirm it on the packet when a bullet is vague. A 125 mm disc with that bore is still the wrong disc for a 115 mm guard.
Should I buy Type 27 or Type 29 for a weld?
For a weld bead on mild steel, Type 29 is the usual shape, worked at about 15–25°. Type 27 is the flatter disc for blending at about 0–15°. Engweld’s UK guide uses those angles. Type is not a quality grade. A title that only prints T29 still needs the label to agree, and 40 grit removes more than 80 grit on that first pass.
What grit should I use for rust, and what for a finer finish?
Engweld’s bands put 60–80 grit on rust and blending, and 80–120 on cleaning and finishing. Heavy weld removal sits around 40 grit on a Type 29 disc. Nisorpa’s box of 50 is 80 grit, for a later pass once the bead is down. A mixed 40/60/80/120 box will not leave one scratch if you use the discs interchangeably.
What rpm should the disc show, and what about 13.3 rpm?
Use a disc whose marked maximum is at least the speed of the grinder, and do not exceed the number on the disc. Most 115 mm listings here print 13,300 rpm. One prints 13,700 and one prints 13,000. MIDO’s spec line prints 13.3 rpm, a listing error, so do not mount that pack until the disc itself shows a real maximum. A missing rpm is a reason to wait.
Is a mixed 40/60/80/120 pack a single grit?
No. It is four grits in one carton, for a coarse pass and a finer pass without a second order. Anesty, MIDO and the Gmozkrn title all use that pattern, and some fields then print only 120. If the title and the grit field disagree, the packet is the one that counts.

Related pages

How to use a flap disc

Flap disc

Best flap discs: PRETEC top pick, Okeno best value

Type 27 vs type 29 flap disc angles for UK weld work

Flap disc vs grinding disc for blend, grind or slit

Sources

Sources taken from the research digest. Prices, stars and review counts are the stored amazon.co.uk listing figures from 19 October 2026.

  1. FEPA safety leaflet — flap discs (retrieved 19.10.2026)
  2. Engweld UK — flap disc guide (retrieved 19.10.2026)
  3. Norton Abrasives UK — flap disc guide (retrieved 19.10.2026)
  4. HSE HSG17 — safety in the use of abrasive wheels (retrieved 19.10.2026)
  5. HSE — PUWER overview (retrieved 19.10.2026)
  6. Cutwel UK — grinding discs explained (retrieved 19.10.2026)