SB305 is 12" long (4.95 mm x 305 mm) and generally used for E-flite, Esky (FP and CP2) and similar CP helis.

Note: On most helis, SuperBooms are designed to be glued in place with CA or epoxy in the same manner as the stock tail boom. The longer SB305 boom used with SuperSkids Landing Gear and some light batteries may make it harder to get a good fore/aft balance, especially when used with aftermarket tail housing assemblies.
If you need to trim (shorten) the boom for better weight distribution, be careful not to make it so short that you have main and tail rotor collisions. Trimming the boom in these cases is the customer's responsibility, not ours. SuperBooms are a stand-alone product designed to work on stock helicopters.