This heater block is based on the E3D Volcano (Version 1) style. This means it uses a thermistor with a glass bead, and is retained by the M3 button head screw.
We round over edges of the heater block which can contact wires. We put the extra TLC into this part to ensure your wires stay protected. We do strongly recommend covering metal surfaces which can contact your wiring with Kapton (polyamid tape).
Also available and recommended are out V1 silicone socks for this heater block.
V1 Volcano style blocks which have the thermistor retained with the M3 button round head screw.
One Aluminum Heater block
Three hardened M3 screws.