Glarks 40Pcs 8 Sizes Round Rubber Spacer Assortment Kit, Multi Purpose Black Round Neoprene Washers Anti Vibration Rubber Spacer Bushings for Electrical Repair and Home Car Accessories

I keep a small bin of rubber bushings and washers for odd jobs in the shop, and the Glarks rubber spacer kit has earned a permanent spot there. It’s a straightforward assortment—40 black neoprene spacers in eight sizes, five pieces per size—housed in a tidy compartmented box. Nothing flashy, just practical parts that solve vibration and leveling problems quickly.

What’s in the box

The kit spans a useful range of diameters, heights, and inner diameters. The sizes (OD × height × ID) are:

• 12 × 7 × 6 mm
• 20 × 8 × 10 mm
• 20 × 20 × 10 mm
• 25 × 6 × 10 mm
• 25 × 10 × 10 mm
• 30 × 7 × 10 mm
• 30 × 15 × 10 mm
• 40 × 10 × 12 mm

That mix skews toward 10 mm ID (good for M10 bolts and as loose sleeves on M8 with a flat washer), with one 6 mm ID part for M6 hardware and one 12 mm ID for M12. Heights range from a slim 6 mm to a chunky 20 mm “puck,” which is handy for leveling tasks without stacking too many pieces. Five units of each size keep the odds high that I can match four corners plus a spare.

The storage box is basic but serviceable. The compartments keep sizes separated, and the hinges and latch have held up to being tossed in a drawer. I appreciate kits that don’t explode on first opening; this one behaves.

Material and build

Neoprene is a smart choice for general-purpose spacers. It’s resilient, resists water and many oils, and remains stable in typical automotive, household, and light industrial environments. In use, these spacers feel firm enough to support load without mushrooming but soft enough to absorb high-frequency vibration. The surfaces have a slightly grippy texture that helps with anti-slip duties under appliances or equipment feet.

Cut quality is decent. The OD and ID are concentric on the pieces I used, and the faces are flat. A couple had minor edge fuzz from the cutting process, which wiped away easily. No visible cracks or voids. There’s a faint rubber odor out of the box—normal for neoprene—which dissipated after a day in open air.

Fit and sizing realities

The ID selection drives the use cases:

• 6 mm ID: Fits M6 bolts snugly. The 12 × 7 × 6 mm size is great for light brackets and electronics mounts.
• 10 mm ID: The bulk of the kit. This fits M10 hardware properly, and can be adapted to M8 if you add a flat washer to center the bolt. I’ve used this with M8 plenty of times; the washer trick works fine for non-critical alignment.
• 12 mm ID: A single size at 40 × 10 × 12 mm. Good for M12 or as a generous pass-through for cable bundles.

If you’re looking for tight fits on M4/M5/M8 without adapters, this kit won’t do it; there are no IDs in those exact sizes. It’s not a precision alignment solution, but it’s excellent as an isolation, spacing, and shimming set.

In use: isolation, leveling, and odds-and-ends

Vibration damping is where this kit earns its keep. I’ve used the 25 × 10 × 10 mm and 30 × 15 × 10 mm spacers under a small air compressor and a benchtop bandsaw stand. In both cases, the “buzz” transmitted through the floor dropped noticeably. The neoprene compresses a millimeter or two under load and then holds position, so the machine stays stable.

For leveling and shimming, the 20 mm-tall spacer is the heavy lifter. I used a pair to even out a utility cart whose casters sat unevenly on a slightly warped deck. The spacers took the load without collapsing, and I didn’t have to stack multiple thin pieces. For smaller corrections under furniture, the 7–10 mm heights cover most needs.

On vehicles and outdoor equipment, the material holds up well. I added four 20 × 8 × 10 mm spacers between a light bar bracket and a roof rack crossbar to cut wind-borne resonance. The squeal at certain speeds vanished, and the hardware stayed tight after a few weeks of mixed weather. Neoprene handles water and road grime without swelling or turning mushy; I wouldn’t put these near exhaust components, but in engine bays or chassis mounts away from direct heat they do fine.

Electrical and electronics work is another practical use. The 12 × 7 × 6 mm size is a nice isolation standoff for mounting small control boxes and power supplies to panels, adding a bit of clearance and decoupling without going to hard plastic standoffs. Because the faces are flat and finish is consistent, contact area is predictable, which helps when you want even clamping pressure across four points.

Performance and durability

Compression set (how much a spacer stays squished after being loaded) is good for this price tier. After a month under a 60–70 lb tool stand, the 25 × 10 × 10 mm spacers rebounded close to original height when unloaded, and the stand stayed level. Under heavy, static loads over long periods, any rubber will take a set. For shelving or heavy equipment that won’t move, I prefer to share the load across more spacers or pick the taller options to keep operating in the elastic range.

Friction is excellent. Even on painted metal, these don’t skate. On tile and sealed concrete, the grippy surface helps control drift from vibration. If you need something truly slip-proof on smooth surfaces, pairing with a thin neoprene pad under the spacer makes the setup almost immovable.

Weather resistance has been uneventful—in a good way. A set used outdoors got rained on repeatedly and showed no cracking or chalking. If you expect prolonged UV exposure, I’d shield them or step up to EPDM, but for typical intermittent sun and rain, neoprene is a solid compromise.

Limitations

• ID coverage: The kit jumps from 6 mm to 10 mm to 12 mm IDs. There’s no tight M8 or M5 option, and nothing smaller than 6 mm. You can adapt with flat washers, but if you require exact centering on M8 without additional hardware, look elsewhere.
• Heat exposure: Neoprene is heat resistant for general use, but it’s not a high-temperature solution. Keep clear of exhausts and heating elements.
• Load creep: Under continuous heavy loads, expect gradual compression. It’s manageable if you select the taller spacers or distribute the load.

None of these are deal-breakers for general repair, but they’re worth noting if you’re planning a very specific fit-up.

Practical tips

• For M8 bolts, use a standard M8 flat washer above the spacer to center the bolt through a 10 mm ID. It prevents side-load wobble during tightening.
• To improve stability on slick floors, add a thin rubber pad under the spacer. It boosts friction without altering height much.
• When stacking is unavoidable, alternate spacer orientations so the faces seat cleanly. A dab of contact adhesive can turn a stack into a single “foot.”
• Label the box compartments with the ID size you use most; it speeds up selection.

Value and who it’s for

As a generalist assortment, this kit hits a sweet spot. You get five pieces per size—enough to kit out four points with a spare—and the dimensional spread handles the most common isolation and spacing tasks around a workshop, garage, or home. It won’t replace purpose-made bushings for precision machinery, and it’s not a substitute for engineering-grade mounts in critical assemblies. But if you want a reliable, grab-and-go set for damping vibration, shimming, and protecting surfaces, it does the job well.

I’ve reached for it to quiet tools, cushion brackets, level carts and furniture, and mount small electronics without transmitting noise. The material quality is consistent, the parts are true, and the box actually keeps things sorted. For the cost, that consistency is what matters.

Recommendation

I recommend the Glarks rubber spacer kit as a handy, budget-friendly assortment for general vibration isolation and spacing tasks. It’s especially useful if you work frequently with M10 hardware or don’t mind adapting the 10 mm ID to M8 with a washer. The neoprene holds up to everyday environments, the thickness options are practical, and having multiples of each size saves time. If you need precise fits for smaller bolts or high-heat applications, pair this kit with more specialized pieces. For everyone else, it’s a quiet problem-solver that earns its keep in the shop.