The FAMCO JPL25 Joist Pocket Liner 25-9 is used to create a pocket in concrete foundations for engineered girders, I-beams, and floor joists. Easily installed with use of preplaced nails. Designed with new construction in mind. Top knockout used for joist placement. The FAMCO JPL25 Joist Pocket Liner 25-9 is used for 1½ inch, 1¾ inch, 2 inch, 2 5/16 inch and 2½ inch wide x 9½ inch tall floor joists. Sold only in 30 units per box. If you have any questions about the FAMCO JPL25 Joist Pocket Liner 25-9, please refer to the FAQs above or feel free to contact us by phone or email.