Showgear TentClamp

these clamps are also referred to as "kader" clamps in some places - but they fit into the running rails on modern clearspan style marquees.
They can take a bit of getting used to if using them for various tasks as the separation between the bolt holes and the upper part of the clamp is very small - so the bolts of the equipment being hung can interfere with the adjustment of the clamp. This means you have to plan out what you're hanging in advance and sometimes mount the clamp empty to start with and add the bolt fitting thereafter. Not a big issue though and would buy again.