The 167 bearing is the only bearing on the market that is designed speciffically for roller derby

The Bont 167 mini roller skate bearing is custom made for Bont by Jesa Bearings of Switzerland. It has a 16mm outer diameter and a 7mm hole hence the number 167. Some skaters call this type of bearing a 7mm bearing. 7mm axles on quad roller skates are popular on high-end plates to save weight. Bont also saved a lot of weight with our mini bearing wheels such as the Royal Assassin and FX1 but there was no bearing in the world that could fit our needs so we designed the 167. 

The Bont 167 quad mini roller skating bearing has an exceptionally fine polished bearing track surface and incredibly precise balls. The lightweight plastic cages allow for lower rolling resistance. The extremely strong steel helps the bearing keep its shape when under load.

Bont 167/688 bearing adapters fit over your 167 mini bearings so that they can fit into 608 wheels. These bearing adapters allow you to use a mini bearing in a wheel that was made for a larger 608 bearing. The benefit of using a mini bearing and an adapter rather than a 608 bearing is that you can create a much lighter set up with better acceleration.