These Cube Inserts just work as intended to provide a clean release. I have had great difficulty removing large cubes from a couple of the typical hard rubber insulated clear cube makers on the market that also make mostly clear cubes, but usually with minor imperfections in shape. My Klaris Mini make 2 perfect cubes every time and these inserts, coupled with simple thumb pressure on bottom, ensure easy release that is missing from other clear cube devices on the market.