Some people like the 3cm fans for the E3Dv6 hotends, I hate this mini fans because in little time they tends to fail or stop or making noises. In a critical component like this, (remember that a failing fan on the E3Dv6 leads you a serious problem) I prefer a secure and silent 5cm blower that lasts ages. There are similar adapter out there, but I designed this to be STRONG. I like strong things. I tried some other designs but I easily broke two of them simply adjusting the screws, so I got mad and designed this. The truth is that I haven't been able to break it. I have my problem solved!!!