First Act Discovery Kid’s Replacement Guitar Strings E & B New. This is an ideal replacement set of guitar strings for your First Act Discovery kid’s toy guitar. The kit is made up of two strings, E & B, which are easy to install and remove. The strings are durable and produce clear sounds which add to the child’s music experience. With recommended age range between 4 to 9 years, they are perfect for children aged 4-7 years old. The strings come from the Educational, Music & Art section of Toys & Hobbies categories.