Pen Sac - Size 16 Straight. 16/64 inch diameter latex pen sac (one of the most popular sizes) for many fountain pens, including Esterbrook, Sheaffer, Parker, Waterman and others.

Pen Sac - Size 14 Straight. 14/64 inch diameter latex pen sac for Sheaffer Snorkels and smaller fountain pens. While totally non-pen related, the smaller sized sacs, usually #10, #12 and #14 are used by model airplane enthusiasts for fuel tanks!