1) It's a "whole RAM": all areas that a VIC can select from a cartridge are covered by this RAM expansion
2) It's easy: a simple 3-position selector lets you choose the configuration as follows:
--- side A) +24k Basic (+8k BLK5, +3k low ram, +2k I/O areas) [total of +37k]
---central) no expansion
--- side B) +3k basic low ram (+2k in I/O areas) [total of +5k]
Note: the 3 positions represent all the three possible configurations that the VIC20 operating system recognizes.
3) It has a RESET button for easy restart of the VIC without any powering off and on again
4) Its shape simplifies the removal and dimensions allow it to be hidden
inside the cartridge door. It can also be assembled inside a common
cartridge shell by simply remoting the button and the sliding lever
(they do not need to be unsoldered to remote)
5) Not expensive at all!