The M:4 is a patent pending 1-piece multi-tool for the M4 carbine designed and manufactured by MultiTasker® in conjunction with B5 Systems, makers of the SOPMOD and SOPMOD-Bravo buttstocks.

The M:4 is precision machined from solid barstock using wire-EDM/CNC, and fits discreetly with no visible footprint inside a specially inletted buttpad made by B5. Easily accessible without tools simply by pressing the release tabs on the buttpad. Dot coded to indicate functions.