Screen-Tight base component (A) attaches to existing vertical or horizontal 2x4 or 4x4 framing with wood screws, roof tacks, or staples. Prepunched holes on 8" centers result in quick and consistent attachment. Cut to desired length using hand-held pruning or sheet metal shears. Made of durable outdoor grade vinyl. 8' lengths, 20 each per carton. Base attaches to a 2x4 or 4x4 wooden frame. Screen spline rolls into the spline groove. Cap snaps onto base. Screen-Tight recommends fiberglass screen (including sunscreen). Color: Black. No. BASE18: Type: Base, Width: 1/-1/2", Length: 8', Color: Black, Material: Outdoor Grade Vinyl, Pkg Qty: 1 No. BASE38: Type: Base, Width: 3-1/2", Length: 8', Color: Black, Material: Outdoor Grade Vinyl, Pkg Qty: 1 Thanks for shopping Hipp Hardware Plus's Online Store for all your DIY and Home Improvement needs. Remember Hipps Help!