Yamaha DTXpress/DTXplorer/DTXtreme

FSRs & piezos...Ok I know what a piezo is, but what's an FSR? 

Today I bought a piezo at Radio Shack to experiment and if I can 
make a trigger. Just took the piezo as it is in it's housing, wired 
it to a 1/4" jack and "shazam" it works!
Though I find that the piezo alone is louder than any of my Yamaha 
pads. I figure partly due to me hitting on the piezo directly itself 
vs an impact of a hit spread out within a pad, and also the Yamaha 
pads have a volume of sorts...?

For $1.49 plus tax it sure makes a cheap trigger!:)