"Vent lid only 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. Excluding the hinge. Usually these measurements are obtained by getting on top of the trailer." [from Scamp description]
I ordered the wrong one from them and forgot to send it back last summer. Still new in the box.