This GOTOH GB7 bass tuning machine has been modified to function as an extender. It allows you to instantly tune your bass's E string (4th string) to any tuning from E♭ to low C.
The Ultra Lite series combines high precision with ultra-lightweight. It not only prevents the head from falling off, but also has a reversible post, so you can use a wrench to reattach it in the opposite direction.
The FreeRange Xtender allows you to instantly downtune your upright bass with a quick flip of the lever. It is attached between the tailpiece and bridge of a steel-string upright bass. By using multiple FreeRange Xtenders, you can instantly switch from bass to cello tuning.