Some people like super sized icons, its nice if you want a special tool bar with big buttons 22px is the default.
Looking at your icons, you can get the beyond compare icons here External compare tool buttons, just enable the script and the icons will be available. Also check out this icons set by sasa S-DOX II Additional Icon Set (177 icons) lots of extra icons, I'm sure you will find something that that you can use.
Finally if you want to make your own icons sets check out this part of the doco Icon Sets.