swa66 - 8:41 am on Nov 7, 2012 (gmt 0)
From what you explain, you seem to use the input coming from the browser to get your hi and lo values ? If that's indeed the case: I'd suggest extreme caution. It's not because you can't select something in a browser that even a wannabe hacker can't give you *any* string they like.
So instead of the explode, I'd suggest to compare the string you get as input from the browser and compare it to the strings you know are in your form, and then in a switch statement set the high and low values yourself, and deal with the option that something else came in just as well.