This is the replacement Complete Carburettor for the O.S. 91 SZ-H engine. FEATURES: Aluminum construction Replaces worn or damaged carburettors INCLUDES: One assembled carburetor One carb O-ring gasket Two 2.6x5mm cap head screws (requires a 2mm hex wrench - GPMR8011) REQUIRES: Installation SPECS: Diameter: .59" (15mm) outside diameter of mounting neck Diameter: .47" (12mm) inside diameter of mounting neck Height: 1.64" (42mm) Width: 3.74" (95mm) COMMENTS: For the carb gasket only, order OSMG6228 kpm01/31/2006 ir/jxs