Video Production Slate

A video slate, or clapper board, can serve multiple purposes in production. When using multiple cameras in a scene, having a slate can help confirm which roll, scene, and take you're looking at in post production. By clapping the sticks together, you can also easily sync multiple microphones as well! Not only can you write and erase easily with a dry erase marker, you can also note who the director and camera operator that are running the production.

B&H Link: http://www.bhphotovideo.com/c/product/292535-REG/Birns_Sawyer_425007_Economy_Dry_Erase_Production.html