The VENT LIDS are extremely thin, in my recent purchase too; but also cheap at $12-$15/each in pairs from Camco; the Vent Lid COVERS (MAXXAIR OR FANTASTIC?) ARE about $25/each w/ 5-year warranty; LIDS, to my knowledge, have no warranty, and MANY, MANY were damaged by recent HAIL STORMS **, (MANY states, nation-wide?); lids take about 5-10-min to replace, if someone didn't mess up hinges w/ Dicor
SPARE LIDS are always a good idea, but many can get by w/ gorilla tape or ETERNABOND TAPE REPAIRS while waiting. (** many recent stories of HAIL going right thu lids, roofs, vent lid covers, windshields)