A foam roller is a large and thick cylinder made of foam that comes in several different sizes and densities. A softer foam roller is best if you’re new to foam rolling or have extremely tight muscles.
You can get foam rollers online or in stores, but generally speaking, it’s worth investing in a good one. If you don’t have a foam roller or can’t buy one, you can use a tennis ball, baseball, kitchen rolling pin with dish towels wrapped around it, or even a hard plastic bottle.