I wanted to see if anyone might be able to help explain a slate / marker that I noticed while watching an episode of The Monkees TV series from the 1960s. Yes, I actually became an avid fan of the show in the late 1980s when I was in first or second grade and the show was airing daily on a local channel. Anyway, this particular episode includes a few outtakes at the end of the show prior to the end credits, and between takes there's a momentary shot of what appears to be some sort of slate or marker, accompanied by an audio cue that's essentially just a buzzing sound (or maybe it's overmodulated tone). As expected, the number increments with each new take.
Out of curiosity, does anyone know what type of slate this was? I'm curious if this was actually some sort of slate that was filmed during production (perhaps even integrated into the camera), or if it was inserted at some point in post or during the audio synchronization process. Thanks to anyone who might be able to help!