CRL Wool Daubers are an industry standard for the application of pinchweld primers and glass preps prior to installation of automotive replacement glass. Because primers can leach out dyes and/or dissolve nylon reinforcement fibers, colored rags or towels can contaminate the primer. This .551" (14 mm) size is more precise reducing the possibility of waste from the application excess primer. Important Notes: Always use clean daubers to apply primers and cleaners. Never put a contaminated dauber back into the primer bottle as this contaminates the primer.