u don't have to cut it open , its a two piece and i has really long shaft carbide burs, and there are no flow bench numbers i had somebody look it over , put it this way the guys flow bench is a work bench now he has'nt had to use it 10 years , and there is no hostility ksanz , i guess that post earlier came out wrong , i might not agree with the kid but he actually has a car unlike some of u shit talking derrelicks