Choosing yours
More than any various other tool, a ratchet will last you an eternity. Quality ratchets could be serviced inexpensively and so should never wear out. Sockets are interchangeable because they’re all standard. Choose the best ratchet you can afford, even if you buy inexpensive sockets to start out with.
Socket release
Sockets will be held onto the ratchet using a bit of spring-loaded ball privately of the square travel. After applying a lot of power, I’ve typically found sockets get trapped on the travel and the only path 
to have them off is usually to hammer the ratchet on the floor or even grasp it in a vice. Top quality ratchets include a button on the trunk which smoothly pushes off the socket while you are ready to release it.
1/4 in . – Used for smaller sockets and precision work. Useful for dismantling individual pieces on the bench.
3/8 inch – The middle sized, and for me, most readily useful size for basic use on a car. A 3/8″ travel can travel sockets of most sizes. It is big enough to use quite a lot of force, but certainly not too big to fit into tight spaces
1/2 inch – 1/2″ sockets are generally utilized for nuts and bolts from around 10mm or more. A 1/2″ travel socket can apply enough push to undo all nuts on a car.
There are also 3/4″ and 1″ ratchets but these are being used on trucks, tanks and commercial Ratchets Wheel machinery.
Tooth count
Inside a ratchet there is a toothed wheel which lets it freely rotate as you tighten the nut. Each just click you hear is usually a tooth passing the ratchet. The more the teeth there are, the much less movement is necessary on the return stroke. A ratchet with 75 teeth will work considerably faster than a 32-tooth ratchet. Making large tooth-counts requires top quality engineering and developing, so as an over-all guide the better quality tools will have an increased tooth count.
Drive sizes
socket-drive-sizes
All ratchets accept sockets using a square travel and mostly there are 3 sizes of drive. All around the world these sizes receive in inches – even though the sockets happen to be metric.