Last summer I accidentally bought this vent lid for my 16' Scamp, then realized my error. It'd cost too much for me to send it back, so maybe someone needs it in the metro area. It's still in the original box. Measures 15" by 22".....(actually about 15.5x22.5) here's Scamp's description:
"Vent lid for WP1320 vent. Used on older Scamp trailers. Vent lid itself measures 15x22 outside of vent lid to outside of vent lid. Color white. To ensure fit measure the plastic vent lid ONLY outside to outside. Usually these measurements are obtained by getting on top of the trailer."
This lid has the piano hinge aluminum strip along one side and the track for the crank/slide. (If you're a Scamp owner, you know what I'm talking about)