It holds heat, most plastics do not stick to it. Perfect in every way. :)

It works just as well as the one that came with my lite6 hotend. Great isolation from any fans, and it's saved my hands several times when I need to reach into my Delta style printer. My only dispute is that it still slips off very gradually if it gets bumped, this can easily be fixed with a stiff wire around the top, or a high temperature rubber band. It stretches to make it easier to attach, but being a soft material, can slip down and get caught on a print once in a long while. Still, totally worth the few dollars on the side of an order. Especially worth the easily cleaned nozzle.

I bought some of these socks to keep my heater block and nozzles clean so i don't get any of that black gunk that appears when the filaments melt to the nozzle and it worked perfectly just the way i intended. however i bought them for my prusa i3 mk2 and i needed to partly take the hot end apart to put it on but no worries i love these silicone socs.

Fits snugly. Very good for keeping heat isolated and plastic off your nozzle. Does add a bit of bulk to the heat block though so pick out your fan ducts wisely.

Awesome product, easy to put on, It adjust to the hot end shape. My hot end is not the original E3D V6 hot end but the Chinese knock off and works great with it as well