Mint TerraLux MiniStar TLE-110
This is the drop in, plug and play 600 lumen LED upgrade for the standard police Streamlight SL20 (note: NOT the SL20X) This unit replaces your entire halogen bulb and reflector assembly. I've used it for just a month or two, and I love it. It gives me the brightness of a modern LED light with the indestructibility, weight, and construction of the Streamlight that I've carried for 8 years.
This is the single mode, full brightness only version. I switched it out for the slightly more expensive multi-mode dimmable version. This one's mint and will come with the box and instructions. They gfor anywhere between $40 and $60 depending on where you check. I paid $45. I'll let it go for $30 shipped.