Fein 42443003043 — genuine Fein circlip / locking washer (M4)
Keep your Fein tool working like new with this original Fein locking washer (circlip) for M4 shafts — a precision-fit retaining ring designed to clip into a 4 mm groove to secure shafts, gears or fasteners. It’s the exact replacement part used in a range of Fein machines, including several high-frequency angle and straight grinders and MultiMaster units (examples: MSfo 852‑1b / MSfo 852‑1c, MSHO 840‑2, and AMM 300).
Why this part matters: the circlip provides reliable axial retention in confined assemblies where a standard washer won’t hold; installing the correct M4 circlip restores the original fit and prevents lateral movement of components that can cause noise, wear or failure. It’s the genuine Fein spare specified for these models, so you get the correct form and fit for repair.
Quick notes for installation: this is a small external/internal retaining ring sized for M4 applications (for a 4 mm shaft/groove). Fit it with appropriate circlip pliers into the groove until it seats fully — once in place it secures the mating parts to the original Fein specification.
