Shoulder rests are used to help violinists hold up their violin. There are many varieties of shoulder rests available, and the selection of a shoulder rest is very personal. Questions to consider when choosing a shoulder rest are: does it help me hold up my violin? Is it comfortable?
Ideally, you should take your violin with you to a music store to test several products. You also may want to ask your violin teacher or violinist friends for their recommendations. Some violin players use no shoulder rests, others prefer a particular brand, and some teachers recommend the use of round, cosmetic sponges - please note you'll need to purchase rubber bands separately if you purchase foam pads or cosmetic sponges (see pictures below for samples). To minimize neck abrasions, some violinists also find it helpful to either place a scarf or cloth over their chin rest, or to use a chin rest cover.