Lip Seals work by retaining the oil inside the air end and keeping air, dust and dirt from entering along the rotating shaft. They come in many standard and no-standard profiles, and many material combinations. Common styles are Metal Cased single lip, Metal Cased dual lip, Rubber covered single lip, and Rubber covered dual lip. Many modern styles incorporate a PTFE lip to make them stiffer and more able to deal with high pressures and aggressive media.
Non-standard seals can often be produced from CNC machined elastomers providing a low cost, rapid turn around supply service.