Comma Wax Seal Anti Rust Treatment & Underbody Protection WS500M 500ml Aerosol. This wax injected fluid is designed for protecting underbody, chassis box sections, door panels, sills, and more. Its fluid nature allows for the elimination or prevention of rust in hard-to-reach spaces. This is a preventative product to help stop rust from developing on the area applied to, typically used when replacing box sections or door sills. Size: 500ml Aerosol.