This combination sash lift/window lock is spring loaded and made of heavy solid bronze. It is a good choice when the meeting rails of the window are not even. (with un-even areas where the window lock goes, a wood shim is used). The keeper mounts on the window sill. The latch base on the sash is 1 7/8" x 1 1/8". the keeper measures 1 7/8" x 3/4".