One thing to watch out for on the TLR series is that most of them come with a universal key (the lug that engages the slot in the rail). While this is close, it leaves play between the rail and key really requires quite a bit of effort on the tension screw to keep the light in place.
There is a 1913 key available from Streamlight for $7 or $8 that precisely fits the rail and eliminates the issue. Changes with one allen head bolt.
Between the LED light and the interchangable key, the TLR series is a really good tool.