Fitting slot 0.17"x1.0433"(26.5mmx4.3mm) Solid nylon construction Simple snap-in installation Easy finger pull operation Fits most horizontal and vertical sliding window systems using this design 1721 is a window travel limit stop. These Vision Industries limit stops work with most horizontal and vertical sliding window systems. This is made by the same company that provides the Window Hardware attached to the most popular brand Windows and Doors sold at Home Depot, Lowe's and many other window and door outlets.