Assorted colorful plastic glazelock shims including square horseshoe shims 4x3 inches with 7/8 inch slot

Glazelock product-family chart showing U-shaped, interlocking, snap-off, flat-plate, tapered, Wedge-Lock, and pre-scored wood shims.

Glazelock graphic showing stacked blue, red, and black interlocking shims above a shim assortment and commercial building photo.

Glazelock application collage showing shims used for tile spacing, window and door installation, cabinetry, and countertop leveling.

Black Glazelock square horseshoe plastic shim with a central open slot and circular molding marks on a white background.

Red u-shaped glazelock shims with rounded edges and embossed circular patterns for square horseshoe slot use

Blue plastic u-shaped glazelock square horseshoe shims with embossed circular patterns and 7/8 inch slot

Brown u-shaped plastic glazelock shims with circular indentation and made in usa flag sticker for square horseshoe use

Brown Glazelock GLZ25 square horseshoe shim dimension diagram labeled 4 inches long, 3 inches wide, and 1/2 inch thick.

Beige Glazelock square horseshoe plastic shim with a central open slot, circular molding mark, and Made in USA flag label.

Glazelock - Leveling Shims

Glazelock® Square Horseshoe Shims, 4 x 3 In, 7/8-In Slot | Multiple Pack Sizes | Made in USA

Name: Glazelock® Square Horseshoe Shims, 4 x 3 In, 7/8-In Slot | Multiple Pack Sizes | Made in USA
Brand: Glazelock
SKU: GLZ21
Price: 108.9 USD
Availability: InStock

A partner brand, sold by FLI Products

Made in USA

No reviews

Regular price$108.90

Shipping calculated at checkout.

Size —

Size

1/4"

1/8"

1/16"

1/2"

3/8"

1/4" Solid

Count

400

500

1000

125

250

In stock, ready to ship
Backordered, shipping soon

Broad 4 × 3-inch profile: A square horseshoe footprint for compatible spacing and leveling tasks.
7/8-inch slot: Positions around compatible pipes, anchor bolts and hardware.
Heavy-duty plastic: A practical shim material for matching to your installation requirements.
Made in the USA: American-made shims offered in assorted colors.

Dimensions and design

Each shim measures 4 × 3 inches with a 7/8-inch slot. This listing is for the square horseshoe, or U-shaped, profile.

Where to use it

Use for compatible window, commercial door, cabinet and countertop installations where the footprint and slot match the project. The open shape lets you position the shim around hardware while aligning the installation.

Check your requirements

Confirm the required thickness, hardware clearance and project specifications before ordering. Do not assume a load capacity from the shim’s dimensions alone.

Material and colors

Heavy-duty plastic in assorted colors. Made in the USA.

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FAQs

What are Glazelock shims used for? +

Glazelock interlocking plastic shims are used for leveling and aligning windows, doors, frames, and other construction applications. Their interlocking design locks stacked shims together to prevent shifting during and after installation.

What makes Glazelock different from regular shims? +

Glazelock shims feature a patented interlocking design that locks stacked shims together so they won't shift or slide out of position — a common problem with standard plastic or wood shims.

Are Glazelock shims Made in USA? +

Yes. Glazelock shims have been Made in the USA since 1997.

What slot width does this shim have? +

This 4" x 3" square horseshoe shim features a 7/8" slot, accommodating larger pipes, bolts, and hardware than standard 1/2" slot shims.

Are these shims color-coded? +

Yes. Glazelock shims are color-coded by thickness for easy identification during installation.