This scientific device allows you to add a reference for size comparison. This ridiculously over-engineered banana splits (see what I did there?) in two halves to house optional suction cups. The two halves are attached magnetically. There is an additional larger magnets to attach the banana to a magnetic surface. If a surface is not magnetic you can take out the suction cups and thread them on.

Magnet (x4): https://www.harborfreight.com/10-piece-rare-earth-magnets-67488.html
Magnet (x1): https://a.co/d/2JZlo05
Suction Cup (x2): https://a.co/d/039h6Ge