Carburetor Carb Fits Stihl Backpack Blowers Sr320 Sr340 Sr380 Sr400 Sr420 Br320 Br340 Br380 Br400 Br420, 4203 120 0601, 4203 120 0603, 4203 120 0605, 4203 120 0607 & Walbro Hd-4a Hd-4b Hd-13b Fits STIHL backpack blowers: SR320, SR340, SR380, SR400, SR420, BR320, BR340, BR380, BR400 & BR420. Replaces STIHL OEM parts: 4203 120 0601, 4203 120 0603, 4203 120 0605, 4203 120 0607 & Walbro HD-4A HD-4B HD-13B. Match original equipment exactly for a perfect fit, easy to install. Aftermarket replacement non-original carburetor.