I don't know about any "keepers" but the center portion of the cover is thicker and it is that thicker part that drops down into the sink - keeping it in place. In our 1969 model Intl Ambassador we don't have these covers - we are the 3rd owners, so .... ;) <http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=2451404230&category=50063>
Tom