2166M-TRV-Tail-Driver-Fitting-Socket-Monument-2166M-p-The-Monument-2166M-TRV-Tail-Driver-Fitting-Socket-has-been-designed-to-enable-fast-removal-&-installation-of-radiator-valve-tails-&-will-fit-most-makes-&-sizes-The-socket-can-be-used-with-a-either-a-cordless-drill-chuck-or-ratchet-with-10mm-hex-socket-p-Monument-2166M-TRV-Tail-Driver-Fitting-Socket