The Wahl Size 40 blade, part 2352-500, is a detachable Ultimate Competition Series cutting head for animal grooming that calls for a very close finish. Its nominal cutting length is 0.6 mm.

The detachable design allows the blade to be removed for changing and cleaning. Wahl describes the series as using a protective coating and tooth geometry designed to help hair feed into the cutting head. Clear trapped hair after use and oil the cutting surfaces regularly.