Old fish feeder mounting question

[kris2001]

I've been using this unknown brand of automatic fish feeder, there is a hexagonal shape cavity on the bottom of the feeder what's the use of it?

Is it because I can put a hexagonal head screw in it and tighten it ? the screws I had at home didn't fit it perfectly it feels like sliding off.

 

[vetteguy53081]

It is meant for a mounting rod that came with it