These are high quality FR-4 double sided and through-hole plated prototyping perfboards.
There are 280 total through-holes with standard 2.54mm (0.1") hole spacing.
Every hole is fully tinned and through-hole plated so that the same hole is electrically connected on both sides of the board.
The rows and columns are labeled with numbers and letters.
Since the boards are FR-4 material they can be trimmed to size with a good set of shears/snips such as tin snips.
Both sides of the board have 24 total (12 on each end of the board) larger soldering pads along the edge of the board.
There are four mounting holes, one in each corner of the board.