
I bought this to use a heavily modified Ender 3 v2 with my 3D printer. I bought the 7mm size which works with v6 type bits as I have a phaetus kite fly that uses v6 type bits. If you are looking for a standard Ender 3 then you will need the 6mm. They are good for removing and installing the hot end (remember to heat the nozzle to remove and install, also use a crescent wrench or channel locks to keep the heater block in a stable position when turning the nozzle on or off screw off). The only problem is that when removing the hot nozzle, it is too tight in the key and it may take some force to remove the nozzle from the key itself once it has cooled. Installing a new nozzle is not a problem as the nozzle is removed right after screwing it in.