This is a large heatsink ideal for cooling high powered LEDs. It is 82mm x 69mm and 35mm thick. It has a 31mm x 27mm solid centre section which is ideal for mounting the power LED to.
All in all, an impressive heatsink with a lot of cooling power and a huge surface area.
Note that the fan mounting grooves shown in the photo don't exist in this current batch of these heatsinks.