When you rip the guts out of the cap, you notice that there is a little o-ring that slips over the LED, and when you slide the LED into position, the o-ring seats into a little notch in the bottom of the cap. This won't hold it into place too well, so I'm still working on getting a rubber grommet like what appears to be on the new Infinity light. I think this can be accomplished easily enough, but I haven't done it yet. My hookup for the LED is as crude as the Photon. The anode can be bent into the shape of a spiral, so it snugly wraps along the inside diameter of the cap. The spiral shape keeps a little pressure against the inside of the cap, but bends into a circle when installed. The cathode comes straight down, then wraps into a tight spiral at its base. This way, when you tighten the light the nipple on the battery presses against this springy little spiral. This requires a little patience with some small needle nosed pliers. As far as a resistor, if you want, you could certainly put one in line with the cathode, but I don't use one. I don't believe in trying to preserve the 11 year continuous use of an LED that will be obsolete long before then anyway.