THIS SET INCLUDES SIX JACOBS RUBBER FLEX COLLETS, IDENTIFIED BY THE SIZES J910, J911, J912, J913, J916, AND J920. THESE COLLETS COVER A RANGE OF TOOLING APPLICATIONS WITH SPECIFIC SIZE RANGES: J910 HANDLES 1/16-1/8, J911 COVERS 1/8-1/4, J912 IS FOR 1/4-3/8, J913 IS SPECIFIED FOR 3/8-1/2, J916 HANDLES 3/4-7/8, AND J920 ACCOMMODATES 1-1/4 – 1-3/8.