Each set includes 3 complete tool kits with 20 inserts per kit "10 each of short and long" for a total of 60 inserts. 2 additional kits can be added later. Thread Sizes = 1/4-28, 5/16-24, 3/8-24 Insert lengths included in kits qty. 10 each of:: Mini Master kit p/n 1204 (1/4-28x.380 / 1/4-28x.500), (5/16-24x.450 / 5/16-24x.620), (3/8-24x.520 / 3/8-24x.750