This is a fixed-width 5cm hairpin lace loom, 20cm in length. They're made of a lovely lightweight aluminium, making them very easy to hold and work with for extended periods.
The metal brace can move up and down, preventing the bottom of the loom from being pushed in while working.
If you're interested in learning hairpin lace I'd highly recommend checking out Youtube to find a tutorial because the movements required to use the loom are tricky to describe. Annie's Online also has a passable class that includes teaching simple and braided hairpin lace.