Sierra 18-4458 Exhaust Protector Valve The Sierra 18-4458 Exhaust Protector Valve is interchangeable with the following: GLM 89260, Mallory 9-44002. Includes stainless steel clamp. Size: 5" and 6". Sierra Exhaust Protector Valve Meets or exceeds the original equipment quality Sierra part number: 18-4458 Interchangeable with the following: GLM 89260, Mallory 9-44002