O.S. Engine OS79871420 Hexagon Socket Head Cap Screw M4x20 10 pcs Pack  [OS79871420]

Product Summary: M4x20 Hexagon Socket Head Cap Screw

The 10-piece pack of M4x20 hexagon socket head cap screws is intended for securing engine mounts, small brackets, and compact fittings on model cars and boats. The specification M4x20 refers to a 4 mm thread diameter and a 20 mm shank length, simplifying selection for replacement fasteners.

These screws deliver uniform clamping where repeatable spacing and torque are required during setup and tuning. Correct thread engagement and careful tightening help protect the tapped holes in structural components. For assemblies prone to vibration, verify proper seating to preserve retention over time.

Practical installation advice includes checking that each screw fully engages the mating thread, removing and replacing any screw with visible head or thread damage, and keeping a small spare stock for on-site repairs. Ten pieces is a convenient quantity for routine maintenance without excess parts.