The HFhSs25C75 standard stainless steel 1/4"-20 x 3/4" threaded flat head screw is used to mount a RRS quick-release clamps to a Really Right Stuff tripod and monopod heads.
RRS has always rejected coin-slotted screws for our quick-release plates, no matter how convenient they may appear. Sufficient torque to properly fix the screw just can't be generated with a coin.
Instead, we've always chosen hex-socket screws to anchor our quick-release plates. Hex keys deliver more than enough torque for the job, are compact, inexpensive, and universally available.
To purchase the correct size hex key for the HFhSs25C75 flat head screw, click here