[Azathoth]

(I)ER hop vs R Hop. The barrel window is cut to extend the length of the patch. Done correctly is better than the R hop. It is a pain to cut the barrel window and if someone has the specialist tools IE The local guy with the CNC machine to cut the window on the Barrel relatively precisely and cleanly then.

The patch material can be the same between the (i)ER and R hop patches however the length is longer on the ER. Honestly, how often are you going to be playing in -20 weather? To quote HS5 from airsoftmechanics, the (I) is suppose to be better in theory at colder temperatures, but no one has written anything credible to show one way or the other the (I) material patch is better at lower temperatures. Just install the standard ER patch, it will be better than the R hop regardless of temperature tbat you are playing and for the handfull of times you are playing in the winter suffer a little knowing that the your ER hop could be 5% better under the freezing conditions you find yourself in.