No. 4 Finish is produced with short, parallel polishing lines. These lines extend uniformly along the length of the coil. It is obtained by mechanically polishing aNo. 3 finish with gradually finer abrasives. Depending on requirements, the final finish can be between 120 to 320 grit. High grit numbers create finer polishing lines and more reflective finishes. The surface roughness is typically Ra 25 micro-inches or less. This is a general-purpose finish, and is widely used for kitchen/restaurant equipment, food processing, and dairy equipment.