Is your Mountfield lawnmower starting to sound a bit rough or losing power? A dirty air filter might be the culprit. This is an aftermarket replacement air filter designed to fit Mountfield lawnmowers with the RM45, RM55, and RM65 engines. It's a direct swap for the OEM part number 1185502570. It's made from decent material to catch dust and grass clippings before they get into the engine, helping your mower run smoothly and last longer. It's a straightforward part - just pop the old one out and this new one in. Super easy to install, no tools needed really. Keeping your air filter clean is one of the simplest bits of mower maintenance you can do, and this filter is a cheap and effective way to do it. Don't let a clogged filter strain your engine. Grab one to have on hand for your next service.