For use with dry erase markers (direct liquid cartridge type) (PM-B501, B502, B503, B513). Do not use with other markers. Oil-based ink (alcohol-based); Material/Cartridge: R-PP; Stopper: PE; Ink Color/B: Blue, D: Black, G: Green, R: Red; Specifications: Approx. 0.2 fl oz (6 ml); External Dimensions (Shaft Diameter / Length): 0.7 inches (18 cm), 2.7 inches (69 cm).