MaxPower s 334300 air filter replacement for for Briggs & Stratton. Replaces OEM # 399877. Fits 3-1/2 HP engines. Measures 4-5/8 in. L x 4-5/8 in. W x 7/8 in. H. Maxpower s extensive line of filters are manufactured to meet or exceed OEM specifications. To ensure a proper fit please check your owner s manual to verify the proper replacement filter number and be sure that it matches one of the OEM numbers listed in this description.