Alltrade Powerbuilt piston ring compressor set 940387 — 6-band ratcheting clamps, 2.88–4.38" range with storage case

The Alltrade Powerbuilt Piston Ring Compressor Set is a six-band, ratcheting clamp kit that compresses piston rings securely for fast, damage-free piston installation.

When rebuilding or servicing an engine, installing pistons without harming rings or cylinder walls requires a reliable ring compressor. This Powerbuilt kit (model 940387) supplies six adjustable steel bands, a ratcheting clamping tool and a heavy-duty storage case with laminated, permanently attached instructions—everything needed to compress rings for pistons from 2 7/8" (73 mm) to 4 3/8" (111 mm). The design focuses on repeatable fit, safe handling and organized storage so both pros and DIYers can work efficiently.

How does this set protect piston rings during installation?

The kit holds rings evenly around the piston circumference so they don't snag or spring out during insertion. The ratcheting pliers allow gradual tensioning for precise compression and consistent clearance, reducing the risk of ring end damage or misalignment.

• Six tapered bands distribute pressure evenly across ring gaps.
• Ratcheting clamp tightens in small increments for controlled compression.
• Bands lock in place to keep rings recessed while inserting the piston.
• Laminated instruction sheet shows correct technique and alignment tips.

Which piston sizes and engines will this compressor handle?

The set covers a broad range of piston diameters so it fits many automotive and light-truck applications. Each band is sized to overlap and tighten, letting you match the band to the piston diameter for a snug, secure fit.

• Covers pistons from 2-7/8" (73 mm) up to 4-3/8" (111 mm).
• Six specific band ranges accommodate small-block through many big-bore pistons.
• Suitable for most cars, light trucks and small engines that fall in the size range.
• Band sizes: 2-7/8"–3-1/8", 3-1/8"–3-3/8", 3-3/8"–3-5/8", 3-5/8"–3-7/8", 3-7/8"–4-1/8", 4-1/8"–4-3/8".

What makes the ratcheting clamp and bands durable and easy to use?

The clamp is engineered for incremental ratcheting action so you can tighten without slipping, and the bands are made from robust material that resists deformation during repeated use. Together they provide dependable grip and long service life in a garage environment.

• Ratcheting lock pliers provide secure, tool-assisted tightening and release.
• Sturdy bands maintain shape and pressure under repeated cycles.
• Permanently attached, laminated instructions resist grease and wear.
• Included carrying case prevents loss and protects the kit between jobs.

How simple is it to learn and store this tool set?

Alltrade includes step-by-step, photo-illustrated instructions fixed inside the case, so you won’t need an external manual. The compact case keeps bands and pliers sorted and ready, speeding setup for the next piston job.

• Instructions are laminated and permanently fastened inside the case for clarity and longevity.
• Case compartments keep each band and tool organized by size for fast selection.
• Lightweight, portable kit fits easily on a workbench or in a toolbox drawer.

Who this is for: The Alltrade Powerbuilt Piston Ring Compressor Set is aimed at professional mechanics, engine builders and informed DIYers who need a reliable, versatile compressor for multiple piston sizes. If you frequently assemble engines, restore vehicles, or perform piston swaps and want a compact, durable kit with clear instructions and a controlled ratcheting clamp, this set provides the necessary components to compress rings safely and repeatably.