A suction-cup base is a flexible dish moulded into the bottom of the toy. Press it onto a smooth, non-porous surface — tile, glass, acrylic, a gloss-painted board — and it grips, holding the toy upright and hands-free.

That changes how you can use it more than any other base style. Riding positions, shower walls, the side of the bath, a chair seat: suction turns a toy you hold into furniture you use, which is why people with joint pain or limited grip strength often rate a good suction cup as the most important feature on the sheet.