This is a HSK A63 #M-4071-0129. This shank is designed to secure the probe into a HSK A+C 63 machine tool spindle. Shank guage length is 42.00 mm (1.654 inches), and it is suitable for OMP40 and OMP400 probes.
(M-4071-0129) HSK A63 Shank for OMP40, OMP400, and RMP40
M-4071-0129 | Machine Tool Probes| HSK A63 Shank for OMP40, OMP400 and RMP40 | HSK A63 | Renishaw