I make my own flashers
I buy a large package of the plan green pot scrubbers at the harware store, I also use them for scrubbing pots.
Anyway if you cut a strip maybe half an inch wide and the length the flasher is wide, and I use elmer's glue all, and glue the strip to the very top of the flasherand clam it into place until the glue is dry.
The scrubber has a lot of grip on the fabric of your hose, and is a lot cheaper than velcro.
If you want you can put a strip on both sides of the flasher top.
Robert "the kilted" Lamb