Hi I am preparing a documentary and we will be 2 ppl 1 camera and i sound guy. I think a regular slate might be annoying for the ppl we will interview plus mose hassle for us, I am wondering about the old light slate they used, It gives a beep and a light flash for syncing really simple when you have a lot of material to shoot. Do you guys remember how it was called and if they still make that thing? Thanks