You can't set the delay, it's friction based, so it's quite random. The more gas pressure you have, the faster the plug is forced out of the grenade, and the shorter your fuse is. It's built for duster.
It SOUNDED cool, and it looks nice, but it's totally impractical, has no effect other than noise, is expensive, and just breaks after a few uses (well, maybe not with duster, but then it would be very sad).
We loaded bb's into the chamber (it suggested max 8) - the best we could do was get 6 to fire off at a time. Very sad. Sorry PFI.