This is the Hatori SB-21FH Nitro Pipe Set. The SB-21FH has no pressure tap, and was developed for the OS 91 HR-Z 3D Speed to provide increased torque. When used with O.S. engines it is recommended that you tune your rotor speed and gear ratio to 11,000~14,500 rpm. This is also the preferred rpm range to use during heavy cyclic and collective loads during 3D flight, as torque will drop off after 15,000 rpm.