WR-18 includes 3 switchable calibers (4mm/8mm/40mm) this version is a specially designed, high performance precision colorimeter, caliber 4mm can apply on small area, cambered and other special surface, caliber 8mm is a universal type for many field, also caliber 16mm can be used for huge, texture and pitting surface. It can bring great convenience for the user in the color quality detection on all kinds of measuring material.