How to check which size grind block you need:
- Turn your skates upside down, remove the top nut, the washer and the top bushing with the hanger along with the bottom bushing and the washer.
- Repeat on both sides until just your kingpins are sticking up.
- Measure the inner distance between the base of each kingpin.
This gives you the max size of disco block needed for your skates; ie 72mm kingpin distance = 75mm grind block.