W H A T  B A T T E R Y ? - question

I have a Pentax MV1 with no batteries. (or battery) Could someone tell me what one(s) I need.

You need two silver oxide cells, size G13. There is also an alkaline cell that will substitute, but alkaline do not last as long as silver. These are all readily available from photo dealers.

I have a Pentax MX what batteries do I need?

Exactly the same answer as above - ideally, two silver oxide G13 cells. In the MX the batteries are only needed to operate the metering - all other functions are entirely mechanical.