Custom piston to cylinder wall clearance

Hi
A few days ago I received the custom pistons for my Jeep :happy2:(Supercharguer Stroker 4.6, about 6 psi of boost), but I don't know how choose the piston to cylinder wall clearance.
In the pistons instructions says:
SB aplications 0.0025-0.0035"
BB aplications 0.0035-0.0045"
What is SB and BB aplications?
Are differents the Supercharguer aplications?
Thanks

Those pistons were made for your bore size. Do not worry about it unless your machinist made the bore smaller than you ordered for.

Generally around .004" clearance is standard, some may require a little more and some a little less. Forged pistons will expand more than cast and hypers will be somewhere between the two.