Piston diameter 18 mm

The knee is one of the largest and most complex joints in the body

Easy access oversized external sleeve pocket for goggles

Easy installation with instructions included

Sweater knit 2x2 rib stitch construction wtih woven logo wrap label at cuff

DNA Air Filters - Stage 2 Air Filter Cover for BMW R 18 20-23 Options:Air Filter Cover Piston diameter 18 mmThis filter features DNAs Stage 2 kit eliminates the OEM intake snorkel of BMW model and offers higher performance and better intake sound. This Stage 2 kit is designed to replace the stock plastic air box intake cover. Combined with the R BM18CR20 01 (sold separately) will increase the Airflow, Filtering Efficiency, Power, Torque and Throttle response. The airflow of this new DNA Stage 2 combined ALWAYS with the DNA Stage 1 Air Filter (P BM18CR20 01)