This past season I did a little bit of testing with a rocket steelhead and the Double Bull shoot-thru netting. I set the netting up on my tuning stand with my chrono behind. The netting consistantly knocked off 4 fps (286 => 282). The holes left in the netting were suprisingly small and the mechanical did not open until it impacted my target. Double Bull recommends using two rubber bands on the mechanicals, but I had the same results from using either one or two rubberbands.