The OC clamp was specifically designed, together with Tor VM, for the isolation of heavily broken down posterior teeth as well as aiding during adhesive onlay cementation.
In the below video, Chris demonstrates using the OC clamp for adhesive onlay cementation.
The OC clamp is designed to work as an accessory clamp with the bow facing to the mesial. The offset angles of the tines are specifically to engage deep cervically on even heavily broken down teeth with good stability. The bow is designed to allow the operator to floss contact points during the cementation procedure without interference.
The clamp is available for shipping to the UK and across the EU, you can find it here.