What I call a finger comb. Its a bunch of long wire "spokes" like fingers and its the best thing out there that ive found.If the fins are bent flat you need to use your pocket knife to get them standing up a little and use the comb. After some practice you should get to where it opens them fairly well. I found it works best starting low and raking up. Also get below to bent fins far enough to get the fingers running deep and keep comb handle 90deg. from coil and with practice you should do fine.