FitBest Replacement Carburetor for Stihl Backpack Blowers SR320 SR340 SR380 SR400 SR420 BR320 BR340 BR380 BR400 BR420 & Walbro HD-4A HD-4B HD-13B New quality replacement carburetor produced by OEM factory 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 Replaces part # 4203-120-0601 Match original equipment exactly for a perfect fit, easy to install