Here's what you'll need:
for tennis raquet grips. - This one happens to be Prince, but any thin cheap overgrip will work.
2. Adhesive backed hook and loop fastener. - I had some genuine Velcro
About 10 in. / 260mm of the loop side of the fastener,
about 2.5in. / 60mm of the hook side of the fastener,
and about 7.5in / 200mm of the overgrip tape.
You can adjust these to the size of your flash head.