The Bosch MS4091C is a comprehensive 91-piece drilling and driving mixed bit set designed to handle the full range of everyday fastening and drilling tasks. Featuring both driver bits and drill bits in a single organized kit, this set delivers all-in-one convenience for professionals and DIYers alike. The set comes with a sturdy carrying case to keep all components organized and protected.

The 91 pieces include 30 drill bits and 49 screwdriving bits, along with 8 nut driver bits and additional accessories. Drill bits cover three types: titanium-coated twist bits in sizes from 1/16" to 1/4", rotary masonry bits from 1/8" to 3/8" for concrete and tile applications, and brad point bits from 1/8" to 3/8" for clean holes in wood. Driver bits include 1-inch and 2-inch insert bits in Phillips (#0–#3), Pozidriv (#0–#3), Slotted, Torx (#10–#40), and Allen hex configurations. The split drill bit tips provide easy drilling starts, and the driver bits are engineered to reduce screw head damage through improved bit-gripping power.