Discuss the use of spiral retaining rings in 'Blind Hole' installations.

Installing a retaining ring in a blind hole (where the bottom of the bore is not accessible) requires an internal spiral ring and a deep-reach installation tool. The tool must compress the ring sufficiently to clear the bore diameter while guiding it to the groove depth. A 'plunger and sleeve' setup is typically used. One challenge in blind holes is ensuring that no debris is trapped in the groove, which would prevent the ring from seating. Furthermore, removal from a blind hole is significantly more difficult; a removal notch is mandatory, and special 'puller' tools may be required to hook the notch and unwind the ring from deep within the assembly.