New Solvent Resistant Cap Top for Roland, Mimaki, and Mutoh Printers with Epson DX4 printhead . These devices (1) prevent the print head from drying out when parked, and (2) they assist in priming/sucking out ink from the head. Cleaning the print head will be prevented and suction will be lost if the rubber around the cap top is bent, brittle, or dirty. This will result in misfiring and print head clogging. Regularly inspect the Cap Tops and replace when necessary