I really wanted to see those great foam inserts on my speakers even though I'm not ready to permanently install them yet.
A long time ago I had some Cerwin Vega speakers with foam grills that attached to the cabs using velcro and thought I would try that to install these inserts.
Since the foam is very coarse I looked at the hardware store for the velcro kit with the biggest hooks I could find.
Velcro Extreme, specifically designed for rough surfaces, had the biggest hooks. The kit contained five 1 inch by 4 inch strip pairs (hooks and loops) with adhesive revealed by peeling off the non-stick backing.
I figured I would use two strips, cut into eight one-inch squares, for attaching each insert.