It is like a Head set. It only fits on 1.5" head tube. It has some cups that allows you to fit the suspension not in the normal way but a bit slacker so it gives you a slacker head angle. You can search here on Pinkbike for a review of that. They made one less then one month back.

The spring was a 300 so it was supposed to be very soft

At first it didn't but I sent it to a suspension mechanic and now it's the best I've ever experienced

It has already been sold