radio shack sells 2 different ones. they have the 2pack that has the IR photoreceptor and the ir led and the led in that pack is 20ma i think.

the other is the high output IR at 100ma and thats what i am using on all my pens so far and it works great. just make sure you have the proper resistor to pump its max voltage. i always use 1.5 through my LEDs so when you plug your rig into the LED calc, tell it you want 1.5 forward voltage for each LED