Better circlip pliers handle both internal and external clips, and offer a multiple tips for different-size clips.
Call them circlips, snap-rings, retaining rings or Jesus clips, they're all the same things. Essentially, circlips are flat pieces of circular spring steel used to retain components on shafts or in housings. Although they come in a variety of sizes and styles, fundamentally there are only two types: internal, which are typically used to hold a seal or bearing in its bore, and external, which are used to locate components on shafts.
Circlips are described by type and construction, i.e. internal or external, stamped, machined or wire. With the exception of the wire and machined clip, circlips normally have ears or tangs that accommodate special pliers so they may be removed and installed without damage.
External circlips are often used to retain things that float on their shafts, such as countershaft sprockets. In this case the sharp edge of the clip should face away from the sprocket.
The most common circlip is stamped steel. It's also the most widely abused. During the manufacturing process, a chamfer is created on one side of the circlip and a square, sharp side on the other. Whenever the clip is installed, the sharp edge must face away from the direction of thrust. The sharp edge can be easily felt with your finger, so there are no excuses for not getting it right. Machined clips have two parallel surfaces so they can be installed any which way, as can round wire circlips.
Circlips are inexpensive, so any time one is removed, replace it with a new one. This is particularly true of the wire type, which is most often employed to hold piston pins in place, and the machined type, which can be difficult to remove without damage. It goes without saying that the proper tool should be used to avoid damaging the clip or your fingers.
Lastly, both metric and SAE sizes are available, but they are most definitely not interchangeable, so be careful not to confuse them.
For more articles on how to maintain and modify your motorcycle, see the Tech section of MotorcycleCruiser.com.