The Gator Cases GP-XLA-MHH Marching Hi-Hat Attachment permits you to mount any of a variety of accessories to your drum. Sometimes you need a cymbal, sometimes a cowbell, sometimes a ribbon crasher but here's the tool that lets you do it.
This accessory securely mounts to the drum rim but will not affect the sound. The F-clamp design is in two pieces, one piece fits to the drum while the rod slides inside the clamp and holds whatever instrument you need (cowbell, etc). Sturdy thumb knobs secure the clamp and rod. The entire assembly is readily removed when it is not needed. The memory lock feature helps you with quick setup since you'll always have the accessory mounted where you want it.