The is the O.S. Speed T-2090SC Complete Tuned Silencer Set.
FEATURES: Fits the O.S. 21XZ-B, 21VZ-B, 21-VG, 25XZ, 28XZ and 30VG engines
          Aluminum construction, polished natural finish
          EFRA-2089 noise rating
          Tuned for 1/8 scale offroad truggy applications
          Pressure nipple preinstalled
INCLUDES: Header Pipe, Muffler, two Long Springs, three Short Springs
          Engine to Header Gasket and Header to Muffler Gasket
REQUIRES: Fastening to engine and supporting other end of muffler to vehicle's
            chassis
SPECS:    Length: 6.6" (167mm)
          Diameter: 1.4" (35.2mm)
          Exhaust Outlet Diameter: 0.31" (8mm)