This replacement air purge primer bulb restores reliable priming for compatible snow throwers and blowers. It is a directfit replacement for worn or cracked primer bulbs, helping engines start more easily after storage or extended use. Key benefits Restores reliable starting: Replaces damaged primer bulbs to ensure the carburetor receives the proper fuelair mixture for easier cold starts. Direct compatibility: Fits models AV520, HMSK100, HMSK105, HMSK110 and matches part numbers 75110639, 95110639, 570682, and 570682a for straightforward replacement. OEMfit performance: Designed to match original dimensions and fitment so installation is quick and maintains factory operation. Durable construction: Built to withstand routine use and repeated priming to extend the service life of the fuel system. Simple maintenance solution: the bulb to resolve issues like hard starting, excessive priming effort, or visible cracking and wear. Attributes Function: Primer bulb for priming the carburetor and assisting with engine starts. Compatibility: Compatible with listed AV520, HMSK100, HMSK105, HMSK110 models and corresponding part numbers. Fit and size: OEMfit design to match original bulb dimensions and mounting points. Performance: Restores consistent prime action and smooth starting behavior when fitted correctly. Typical use scenarios Winter service: a brittle primer bulb before the snow season to ensure the snow thrower starts reliably in cold conditions. Maintenance between seasons: Swap the old bulb during routine maintenance to prevent hard starting after storage. Onthespot : a cracked or leaking bulb to restore normal priming when the engine struggles to start or requires excessive pumping. Installation guidance Intended as a direct replacement for the listed models and part numbers. Installation is straightforward for most users; consult the equipment manual for specific removal and fitting instructions. This primer bulb provides a practical option to restore proper priming and starting performance for compatible snow throwers and blowers.