Grover started to produce a few guitar and banjo machine heads in late 1800. Then, they expanded into different machine heads such as guitar, violin, ukulele, mandolin and etc... Grover is one of the world's finest string instruments, while many years have passed they still provide the finest products for musical industry. To provide top line quality, they provide a lifetime warranty for machine heads. If tuners fail, customers can return the products back to us with a free charge of repair or replacement.