Standard linear bearing seals - the basic seal offered by most recirculating linear guide manufacturers is either a single- or double-lipped style. These seals make positive, line contact with the rail, for good protection against both fine particulates and liquids. Double-lipped seals provide two barriers between the external environment and the internal components of the bearing, and are often used for very fine dust — such as ceramic or glass — and hazardous chemicals. Some manufacturers also offer triple-lipped seals as an option.