Playing small percussion instruments is a great way to target several important developmental skills.
Children develop bilateral motor coordination while using a two handed instrument such as the wood blocks, claterpillar, rhythm sticks, sand blocks, and my personal favorite, the percussion frog.
Playing instruments helps develop your child's attention and listening skills. Have them play fast or slow, soft or loud, up high or down low, etc. As skills develop you can include directions like putting the instruments on the ground and performing an action. For example "put your instrument on the ground, clap three times, now pick your instrument up." Increase the number of verbal directions as skills develop.
Kids often love the anticipation created by a "play and stop" game. Change up when the "stop" comes to keep them listening and engaged. This game develops attention and impulse control.
When kids play instruments in a small group they develop social skills when passing and taking turns.
If you're looking to add some small percussion to your home, class, music group I recommend West Music. When I order online I typically order from this company and have been pleased with the quality of the instruments both in sound and durability.