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Flat packers vs horseshoe packers

Updated: 23 October 2026

You have a screw already in the frame and a solid plastic plate that will not go past it. Flat packers vs horseshoe packers is that access problem, plus a third shape. Use a horseshoe when the fixing is already started, a flat when you can place the piece first, and a bridge packer when the rebate has to drain. This set sells flats and one U-shaped listing. It does not sell a bridge packer. The ranked table is the [glazing blocks comparison](/hub/diy-supplies/glazing-blocks). Peter F. checked the listings. This is not a lab test. A qualifying purchase can earn a commission at no extra cost to you.

You have a screw already in the frame and a solid plastic plate that will not go past it. Flat packers vs horseshoe packers is that access problem, plus a third shape.

Our top picks

FUX FUX 100-piece glazing packers

Best overall

FUX FUX 100-piece glazing packers
8.8/10about £11.99
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Eleechen Eleechen 72-piece glazing packers

Best value

Eleechen Eleechen 72-piece glazing packers
7.4/10about £5.99
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n/a U-shaped PVC glazing packers

Alternative

n/a U-shaped PVC glazing packers
0.8/10about £12.99
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On this page
  1. 1.What the slot is for
  2. 2.What a flat packer can and cannot do
  3. 3.Bridge packers are the third shape
  4. 4.The one U-shaped listing here

What the slot is for

A horseshoe packer is a plate with a slot, so it can slip around a screw that is already part-way in. You then tighten, and the packer stays as the spacer. Olympic Fixings sells a trade horseshoe around 101 × 43 mm, which is not in this amazon set. The Glass and Glazing Federation’s section 3.12 puts installation packers beside the fixings, left in place. The slot adds access, not strength. If you can back the screw out, a flat often does the same job. Over-tightening still bows the frame. Horseshoe colours are not flat-packer colours. If you mix the bags, measure both.

What a flat packer can and cannot do

A flat packer is a solid rectangle. It has to be there before the load. You cannot post it past a screw head. In the rebate you place setting blocks, lower the unit, then fit location blocks and beads. It is the wrong shape if the screws are already home and the frame has dropped. Ten of the eleven listings are flats. About 100 × 28 mm is the everyday glazing size, on EVOGES, Eleechen, the HuangXinyu 72-piece set, and Vurixfo. Yonfas claims that size and prints 1 × 2 × 3 cm as well. The FUX 100-piece set is 100 × 24 mm. The 60 × 40 mm flats are shims. Area is not a slot. Flats can do toe and heel, which is a diagonal, not a shape. Keep them off the drain. Glazing Supplies Direct uses horseshoe and bridge in overlapping ways. A grooved FUX face is not a horseshoe and not a bridge.
FUX FUX 100-piece glazing packers

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FUX FUX 100-piece glazing packers
8.8/10about £11.99
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Bridge packers are the third shape

A bridge packer supports the sealed unit and leaves a path for water. VEKA’s Norscot guide uses bridge packers on the lower rail, minimum two, and more if the rail is longer than 1,500 mm, and keeps glazing blocks off the drain slots. The packer should be wider than the unit. Their example is 30 mm under a 28 mm unit. A flat or a horseshoe laid on the slot can dam it, because the horseshoe slot is sized for a screw, not for the drain hole. None of the eleven titles is sold as a bridge packer. If the diagram shows one, buy that component. Do not substitute the U-shaped listing or a grooved FUX flat.

The one U-shaped listing here

The only horseshoe-style product here is B0H5BYTQJ8, 80 PVC pieces at about £12.99. The bullets say a U-shape that can be used without pre-drilling. Product dimensions are 6 × 4 × 0.1 cm. The title and the bullets disagree on the thicknesses. There is no Customer Reviews line, and the included-components field says a scraper. That is why it is not a pick. Open the live amazon.co.uk page before you rely on the thickness list. Horseshoe if the frame screw is already started. Flat, around 100 × 28 mm, if you pack before you fix and the rebate accepts that width. Neither replaces a bridge packer. This set can cover the flat, might cover the horseshoe after you resolve that listing, and does not cover the bridge.

Common questions

When do I need the slot?
When a screw or frame fixing is already in and you still need a packer beside it. The horseshoe slides around the shank, and you tighten afterwards. If you can place the packer first and fix through or beside it, a flat packer does the same spacing job without a slot. The slot is access. It is not a stronger plastic.
Can a flat packer do toe and heel?
Yes, if you can put it in before the glass bears on it. Toe and heel is the diagonal that stops an opening sash dropping: on a side-hung window, Conservatory Land’s note uses bottom packers on the hinge side and top packers on the handle side. Follow your system if it draws that diagonal differently. The flat’s limit is drainage and width, not the word toe.
Is a horseshoe packer a bridge packer?
No. A horseshoe is slotted for a fixing. A bridge is shaped so water can pass under the glass in the rebate. Glazing Supplies Direct’s article sometimes uses the names in overlapping ways. VEKA treats the bridge on the lower rail as its own component. A U-shaped amazon listing is not that component, and a grooved flat is not that component either.
Which captured product is U-shaped?
Only B0H5BYTQJ8, at about £12.99, PVC, 80 pieces, dimensions field 6 × 4 × 0.1 cm. The title and the bullets disagree on thicknesses. There is no star line in the set. The other ten listings are flat plates, either about 100 mm long or 60 × 40 mm.
Can I pack a frame with only flat packers?
Yes, if you pack before you drive the fixings, or if you can withdraw a screw to slip a flat in. The federation’s rule is the position, beside the fixings, not the slot. Doors still want extra packers at hinges and locks. If the anchors are already tight and the frame has slipped, flats will not pass the screw heads, and that is when a horseshoe earns its place.

Related pages

How to use glazing packers

Glazing packers for window fitting

Glazing packers buying guide

Glazing blocks

Best glazing packers UK with a top pick and a limit

Sources

Public UK sources and the amazon.co.uk listings compared on this page. Listings captured 21 October 2026.

  1. GGF installation guide, section 3.12 (retrieved 21 October 2026)
  2. BSI BS 8213-4:2016 summary (retrieved 21 October 2026)
  3. FENSA homeowners (retrieved 21 October 2026)
  4. GOV.UK building work, replacements and repairs (retrieved 21 October 2026)
  5. Glazpart glazing accessories (retrieved 21 October 2026)
  6. VEKA Norscot installation guide (retrieved 21 October 2026)
  7. Sidey survey and installation guide, December 2024 (retrieved 21 October 2026)
  8. Glazing Supplies Direct: how to use glazing packers (retrieved 21 October 2026)