Used together with Park Tool HCW-4, this guide ring holds your spanner securely in place so you can install the drive side of a Sugino 75 NJS bottom bracket or Sugino 75 Super Lap bottom bracket, without worrying about the spanner slipping off the cup and making you say bad words.

Can you install a Sugino 75 or Super Lap BB without it? Of course, but once you use it, you'll never want to not use it ever again!