To hold things, like your shampoo bottle, razor, deodorant, even the soap in the bathroom, or for that shower at the camp ground, or hold the cooking oil in the kitchen etc.
I have safely held a 750ml bottle shampoo on my bathroom wall, but I felt a litre was a bit much.
Some people use these for their remotes, that's okay so long as the remote can handle a bit of moisture as the squid has to be dampened slightly to get the suction.
Best way to get optimum hold is to roll your bottle on to the panel so all the suckers grab.
The side with the smooth section is the one to go against the wall. For cleaning just chuck in washing machine or top shelf of dish washer.
Sold in packs of 4, measuring 8cm by 19cm