Two types of tools for checking common angles. The block on the top in the photo has its corners cut to common angles found on various types of chisels and plane blades. Plates screewed to the block create angled 'pockets' into which an edge is pushed to check the angle when grinding or inspecting. Made from aluminum, the gage can't knick or dull the blades being tested.
The small tools below the block are nothing more than chunks of 1/4" key stock with the ends formed to commonly encountered angles, eg 15, 30, 45, 60 degrees. It's amazing how often these come in handy, especially "sanity checks" on complicated setups. Their real advantage is their small size and consequent ability to get into places that normal angle gages simply won't fit.