The Festool 204384 Bit Cassette BT-IMP SORT4 is handy storage unit with belt clip that includes a 1/4" Lockable Impact Bit Holder (quick-change type) and 5 different commonly used impact-rated 1" (25mm) bits (PH 2 & PH 3 Phillips bits, TX 25 & Tx 30 Torx bits, and a SQ 2 Square Drive bit). A perfect compliment for Festool Impact Drivers.