Description One Size 21-2 Necked Latex Sac, the correct size for Parker Junior Duofolds, intermediate and Junior Streamlined Duofolds, and Wahl Eversharp Equipoise pens.Please note: Price is per sac. Pen sacs are available in many different sizes and materials. Pen sacs are measured in 64ths of an inch diameter. Most sacs will need to be trimmed prior to use and are intentionally made longer than necessary. We offer Free Shipping on all orders over $59 for US customers, and for orders over $250 for our Canadian customers.