Are you talking about their 3.3 pound anchor like this?
https://www.cooperanchors.com/store/p/15kg-33lb-nylon-cooper-anchor
They don’t offer dimensions but if that would fit in my 6-1/8” high swim platform locker I suspect it’s a very small anchor and might not hold even my stern in our high current flows at mid tide times. Our tides here range 3 feet to 4 feet so our water flow speeds are pretty significant. Do you think these Cooper style anchors offer as much or greater pull out resistance as the same weight Fortress, Fluke style anchor on a sand bottom? My 4 pound (FX-7) Fortress Fluke is more than 6-1/8” high. I admit that I don’t need this big of an anchor for anti-swing of my stern while on a beach. Btw, don’t compare weights of a galvanized, steel fluke style anchor to the Fortress brand aluminum fluke style anchor. The Fortress is much much lighter for the same physical size and it’s the physical size that gives the holding power. (A 4# Fortress Fluke = 10 pound galvanized Fluke anchor). If you’d like a lighter weight anchor for the same holding power you’re going to love the Fortress.