MACK X-CALIBER PINSTRIPING BRUSH Part# X-00; (1 Brush) SIZE: 00  HAIR LENGTH: 1-1/2". What makes the XCaliber special is it's short hair length. Only 1-1/2" vs. the average 2" and 2-1/4". This shorter length allows greater control for intricate designs as well as long lines. X-CALIBER Series - Short Length Squirrel Hair Stripers are made in sizes 0, 00, 000, and 0000.