Designed to self-centre, for accurate measuring of bores. Satin finish, fitted with knurled ratchet stop. OXD -335-2520K Micrometers: 11 - 14mm, 14 - 17mm, 17 - 20mm. Calibration ring: 11 and 17mm, slotted screwdriver and spanners x2. OXD -335-2530K Micrometers: 20 - 25mm, 25 - 30mm, 30 - 35mm, 35 - 40mm. Calibration ring: 25 and 35mm, slotted screwdriver and spanners x2.