This is a Taper Shank BT30 #M-4071-0049. This shank is designed to secure the probe into a BT ISO 30 taper machine tool spindle. Shank gauge length is 27.00 mm (1.063 inches), and it is suitable for OMP40 and OMP400 probes.
(M-4071-0049) Taper shank: shank specification BT-1982, taper ISO 30
M-4071-0049 | Machine Tool Probes| Taper Shank | BT30 shank for OMP40 and OMP400 | Renishaw