The BTS 630 and 635S saws feature a new air filter, are easy to operate, and start reliably. The three-stage air filter system includes a cyclonic filter, a foam pre-filter, and a paper filter that ensures the system will last longer than any comparable filter on the market resulting in minimum downtime, reduced maintenance, and reduced lifecycle costs. Also, the durable and rugged design extends the service life. Wacker Neuson. 800-770-0957.