Per Wikipedia:The VIC-1111 16K RAM Cartridge is a Random Access Memory expansion device produced by Commodore for the VIC-20 computer. It plugs into the cartridge port of the VIC-20 and thus provides a total of 19967 Bytes free for user programs (including the VIC-20s built-in 3583 bytes of user RAM). The VIC-1111 is usually housed in a brown utility cartridge style case, although there are a few variations.
By using a slot expander peripheral, the VIC-1111 cartridge can be used in combination with an 8K RAM Cartridge to provide up to 28159 bytes of user available RAM. Upon opening the cartridge and exposing the circuit board, the user can usually find a set of DIP switches (or solder points to attach DIP switches) that are used to change the block where the 16K of RAM will 'mount' in the VIC-20s memory map.
The VIC-1111 16k RAM Cartridge uses the same circuit board as the VIC-1110 8K RAM Cartridge. The main difference between these two cartridges resides in the number of static RAM memory chips internally installed.
A peculiarity of the VIC-20's design is that when an 8K, 16K or 24K RAM expander is installed, the VIC-20's memory map is re-organized. The location of video RAM is changed, for instance. This means that programs written for an unexpanded VIC-20 that POKE or PEEK to the VIC-20's video RAM will not run when an 8K (or larger) RAM expander is attached.

Cartridge only in Good Condition