I'm sure I'll catch crap for this, but I am new here and crave the abuse and criticism but I've been using STL for years and am pleased with them.
You have to understand, your not going to get a Whelen or Code3 product for a third the price; you get what you pay for, a third the quality, a third the price, and a third the customer service
Over the years I have owned 2 TAs (sold me existing set, decided I wanted another one), several dash lights, and even a few minibars.
Here's how I rate them:
STL Slim-6, nice output, nice control unit, nice patterns. It can be seen in direct sunlight on an Oklahoma summer day (that says a lot). At night: BRIGHT!
STL Pro Duo, not too bright during the day, simple switch, easy to mount.
STL Raptor Slim, nice little light if your looking at it head on. Of course I do not care about off axis and REALLY being seen, so thats a good thing I have this light! The clear dome on it lets light right in and starts cutting the output instantly. My solution? Plastidip. The bar is on top of a black vehicle, so making the top of the bar black lets it blend in. Not to mention, not letting the sunlight get to the unit until it leaves the bar, makes it much brighter. Because I have to alter the light to make it semi-effective, and probably void any warranty by altering the device, but its ok, since I anticipate it failing and needing to be replaced anyway
I have had to replace a module in my STL Raptor, but it was a REFURB unit to begin with. Probably would have had to do the same thing if it was BNIB, but thats fine, since I do not really care about quality!
Also, the Slim-6 and the Pro Duos are not rated for exterior use. I'm a storm chaser and I had them in some TORRENTIAL downpours, not so much as a single LED burned out yet
I am slowly upgrading my equipment to Feniex, but if you need decent lights on a budget, STL is the way to go because it is always smarter to waste MORE money instead of saving it up and putting it towards something worth your money and time!