Saturn Booster Pack 4M Plus

A few weeks ago I bought a Saturn Booster Pack 4M Plus (Action replay, 1M/4M RAM, Memory Card in one) It has a switch on the front of it and, since it came with no manual, I have no idea what it does. I'm alomst certain it doesn't change it from 1M to 4M. Does anyone know what this switch does??
 
Top