The Macsim Hex Insert Bit 4mm × 25mm is a precision-machined tool-steel driver with a hardened tip that delivers higher torque transmission and longer service life when fastening metric socket-head screws. Features + Benefits: High-Grade Tool Steel: Resists wear and rounding for a consistent, accurate fit.Hardened Tip: Maintains edge integrity under high load, boosting driving power and reducing cam-out.Exact 4 mm Hex Profile: Ensures snug engagement with metric cap-screws and set-screws.Compact 25 mm Length: Ideal for use in magnetic bit holders, cordless drivers, and tight spaces. Product Uses: General assembly, machinery maintenance, cabinetry installation, automotive and engineering tasks requiring reliable 4 mm hex fastening. Pack Size: Supplied as one 4 mm × 25 mm hex insert bit (multi-packs available on request).