Will the shimano Zee M640 fit my bike I have the carrera vulcan it has the Clarkes  exo hydraulic brakes.I what to swap the clarkes for better ones so will the Zee M640 fit my bike if not what other braks will fit my bike
Shimano Hydraulic brakes are often sold as a kit, with the hose already connected to the caliper and lever and the system already bled. These kits are listed according to which hand the lever is for (the front brake's lever can be on the right or left according to country and preference) , whether the caliper is intended for the front or rear (the caliper body is usually the same but the fittings can vary) and hose length (to allow for different frame sizes and suspension designs/travel).

The lever clamp is almost always about 22.2mm (7/8th inch).

The caliper mount on the frame or fork will be IS-mount (bolts from the side) or post-mount (bolts parallel with the rotor).  M640 brakes are natively post-mount.

Adapters are available to fit PM calipers to IS mounts. Adapters are also used if a larger rotor is used. The normal rotor sizes for calipers without an adapter, or using a "+0mm" adapter for mismatched mounts, are 160mm at the front, 140mm at the rear.