1. what exactly are alignment shims and what are their particular uses?

Basically put, a shim is either a washer or thin piece of material which is used to make parts fit, to reduce wear, or - in the case of alignment shims – keep the parts aligned properly so that they can function to their best ability.

stainless steel U slotted shims can have many different applications, such as changing the camber or caster on your car; car wheels can become misaligned over time, and the introduction of alignment shims can help to correct this problem. In this instance, the shims are inserted in between the wheel hub and the car axle, where they then push forward on the hub and the wheel, helping to reduce any metal distortion that has occurred. Alignment shims can also be used in other applications, such as in assembly and weld fixtures.

2.Size and wholesale price as below, Shim size can be customized too:

 Thickness including :
0.01mm, 0.02mm, 0.025mm, 0.03mm,0.04mm, 0.05mm, 0.06mm, 0.07mm, 0.08mm
0.1mm, 0.12mm, 0.15mm, 0.2mm, 0.25mm, 0.3mm, 0.4mm, 0.5mm, 0.7mm, 0.8mm
1mm, 2mm,3mm, 4mm, 5mm 
All stainless steel U slotted shims can be customized according to your samples or your drawings!