Another top quality tool designed MRB, used every other day at Lambretta upgrades it makes fitting the small mag housing seal much easier, and far less chance of ruining your seal by using a socket!
 
Offer the seal into position, fit the tool in place and press down straight, if need be - lightly tap the tool with a small hammer to make sure the seal is fully home. 
 
Made from nylon so you don't damage the seal.
 
It's a must have tool if you're serious into rebuilding engines.