I don't really know what this drum part is for - but a quick google has indicated that it is for a marching band drum - a mount that allows an easy quick release apparently.  Hopefully, if you are looking at this - you will know exactly what it is for, and how it is used.  The part number is 3996, and it is described as an XL QUIN ADAPTOR-HTS.

Unused, this is old shop stock. The packaging is a little tatty - but the item is in new condition.

You will receive both of the mounts shown in the photographs - because I don't know if they are supposed to be used in pairs, or if one is all that is needed.

Hopefully I have priced them correctly (to sell) - because I have not been able to find anything to compare them against.

Any questions, please don't hesitate to ask.