Snap ring pliers are one of those tools that you never think about until your suspension fork is in pieces on your workbench. If you don't have the correct tool, you'll have to make a trip to the hardware store and hope they have what you need. Be proactive and make sure you're ready for your repair by reading the instructions ahead of time, and purchasing any tools you don't already have, such as the Park Tool RP-1 0.9 mm Straight Internal Snap Ring Pliers. The RP-1's are made from forged, heat treated chromoly, and have vinyl dipped handles. Internal snap ring pliers have reverse opening jaws—when the handles are squeezed, the jaws shut—and these have 0.9 mm tips to fit in the snap ring's holes.
Internal snap rings are split rings which reside within a groove cut around the bore of a hole, held in place under their own tension. Internal split rings are often found in damping assembly cartridge housings within suspension components and hydraulic dropper seatposts.