Rocker switch query

So I've been working on small amps and guitars to further my knowledge in the area and I've run across a few problems thus far, one concerning a particular amp (small, solid state practice amp) and its loose on/off rocker switch. I want to replace this switch but when I go to order one online I'm confronted with an insane amount of options. I've found one that resembles the piece but what all do I need to know about the size of the switch, etc? Any tips or insights would be appreciated. Thanks.