Old button caps will not work where they are missing on this unit.
The unit operated correctly. It does not have two button caps.
It was not until I removef the button caps from my non-functioning unit to put on the new unit that I discovered they do not fit. The bases on the new unit are larger with different attachment design. My car is 2000 Volvo V70 base. Shipped it back at my cost and received a partial refund.