We're using this shoulder support on a 1/16th violin. Unlike the plastic/metal shoulder supports that we never quite managed to set up just right, this rigid foam block was immediately usable.
We wrap the included rubber bands around the end pin and waist in a V shape, and then wedge the shoulder support underneath the rubber bands (flat side to the instrument, lower part towards the chin rest). This is easy enough to do even for a four year old.
The support it provides to the player is good. The foam is rigid enough to not deform, but soft enough to be comfortable on the collarbone. Unlike simple round pads it has the right curved shape to support the violin more towards the chest.
On a 1/16th violin the rubber bands might be a tad too long; they don't quite prevent the shoulder pad from moving.
The dark grey rubber bands across the top of the violin don't look pretty, but that's okay. I still prefer this shoulder pad over all others that I tried (e.g. the round Magic Pads, or the rigid adjustable shoulder rests made from metal or plastics). There is no point in using a pretty shoulder rest (especially on a 1/16th violin) when it is uncomfortable enough to discourage playing.
