What is the gadget on this 512k?

[JC8080]

I ran across an ad for this 512k, it has some sort of a box on the back plugged into the mouse port. It appears to have a slider that goes from tortoise to hare, so I assume it controls pointer speed, but I don't know why it would have both a male and female connector. Has anyone seen one of these before?

 

[bigmessowires]

I would guess the male connector is for a PC style serial mouse. https://msusurplusstore.com/products/microsoft-lr-84783-9-pin-serial-mouse

 

[Nixontheknight]

I would guess the male connector is for a PC style serial mouse. https://msusurplusstore.com/products/microsoft-lr-84783-9-pin-serial-mouse

honestly would be cool if somebody reverse-engineered one of these because serial mice are way easier to find than Macintosh ones, and I'm sure certain PS/2 ones would work in a serial to PS/2 adapter

 

[VMSZealot]

I haven’t tried it myself, because I have no need to, but could this be the tool you are looking for? (Serial Mouse Driver)

It seems you can use a serial mouse with your Mac!