This is a nice reasonably weighty drain cover. I like the optional suction cups - I've tried it both ways and don't really feel the suction cups are needed but they're there if you want them.
There's nothing like a terry towel for scleral lens safety, because a towel will both prevent lenses going down the drain and make sure they don't crack if they land a porcelain sink. However, if the only real worry is making sure they don't go down the drain, a rubber drain cover is very helpful.