Milwaukee 43-72-0550 Bit HolderThis is a genuine Milwaukee part.It attaches to the bottom of the housing on a Milwaukee cordless drill.Its purpose is to hold the small screwdriver bits that are inserted into magnetic bit holders.It is compatible with the Milwaukee tools shown below.This part is compatible with the following machines:Milwaukee2601-20 (SER B28A) 1/2" Compact Driver Drill2601-22 (SER B28A) 1/2" Compact Driver Drill2601-20 (B28B) 1/2" Compact Driver Drill2601-20 (B28C) 1/2" Compact Driver Drill2601-20 (SER B28D) 1/2" Compact Driver Drill2601-059 (SER D36A) 1/2" Compact Driver Drill2601-059 (SER D36C) 1/2" Compact Driver Drill2601-21 1/2" Compact Driver Drill2602-22DC M18 1/2" Compact Hammer Drill2606-22CT M18 1/2" Drill Driver2607-20 M18 1/2" Hammer Driver2607-22 M18 1/2" Hammer Driver2607-22CT M18 1/2" Hammer Driver2750-20 (G41A) M18 Brushless 1/42702-20 M18 1/2" Compact Brushless Hammer Drill/Driver