There are (7) handles, each one for a different measuring range:

• .080" to .250" (2-6mm) - 54-364-556-BT
• .250" to .375" (6-10mm) - 54-364-550-BT
• .375" to .750" (10-20mm) - 54-364-551-BT
• .750" to 2"  (20-50mm) - 54-364-552-BT
• 2" to 4" (50-100mm) - 54-364-553-BT
• 4" to 8" (100-200mm) - 54-364-554-BT
• 8" to 12" (200-300mm) - 54-364-557-BT