Really good quality solar charge controller. One of the best on the market in that class of chargers among those I could find. Very competitive price. The only problem - documentation. I couldn't find any information in the manual on how to set up the battery type for the acid battery. So I had to google this. Below is the useful information which might save your time.

SLD - Sealed Lead Acid Replacement Batteries. Just a regular car acid battery to start the engine.
GEL - Gel batteries are called gel because they use silica. Same as Lead Acid but gel instead of acid.
FLD - Flooded Battery: A flooded deep cycle battery is a battery that has thick plates, large separators, and high-density paste material.
LI - Lithium. Probably means LiFePo4 batteries type. Also called a deep cycle battery. Has almost the same charge cycle as for acid and gel batteries type. The only difference - you can pick the final voltage on the battery which is nice.

Yes , really small ! All functions are here and more .
But different from other Renogy controller : this one doesn't show daily charge and discharge!
No control over load disconnection, it cut it off at 11 volt .
It continuously flipping through display screens and no way to stop it - really annoying !
But overall good device, useful !

I have 2 of these. One on a 30w and another on a 50w Renogy panel. They do what they do and just work.

To avoid confusion, this references the Renogy 10 Amp 12V/24V PWM Negative Ground Solar Charge Controller Compact Design w/LCD Display.

Renogy seems to be among the leaders in our ever-growing world of solar technology. I have two of the cheap (under $10) PWM controllers, and they work okay, but for the price, I happily upgraded to the Renogy controller. Briefly:

Pros:
Economical.
Will connect to a Renogy BT module (sold separately)
Tells me most of what I need to know in its LCD menu.
They do have customer service ( but reviews of this are mixed. )

Cons: Terminals seem to be designed for wire 12 AWG and smaller. I got 10 AWG in there, but I won't trust them to stay.

A reminder, PWM is not the best type of charge controller, but if your needs are modest and you have no shade to interfere with your solar energy collection, it works pretty well. This 10 amp controller is good for your basic needs, handling up to two, 100-watt panels in parallel (series might be right at the limit). It works with all the major battery types, but you need to manually set Lithium types.

If you want or need a more sophisticated solar energy setup for your home or large RV, you will likely want the much more expensive offerings from Renogy, Victron, and others. But for a small camper or backyard project, this is quite adequate. When I'm done playing around with it, I plan to affix it to one of my Renogy 100-watt suitcase solar panels.

Need cheap and simple? Buy it.

Happy solar, all!

UPDATE: So after an entire summer of operation, this controller has worked exceptionally well. My single concern of it being in an enclosure that got too hot in the summer sun was eradicated. I never had to turn the little cooling fan that I installed in the box on. As far as I know, it never shut down due to heat. It did, however, save my 12V battery when I left the pump on all night. It cut the power after it got to somewhere around 10-11 volts (the limit is in the manual) and resumed operation when the solar panel charged it to the proper threshold. Great value in this tiny controller.

After reading others' reviews, I don't know what some people expect from this unit. It is ridiculously cheap and works exactly as advertised. I have it connected to a 12v battery running a DIY solar water setup for my stock tank pool, and it is EXCELLENT! It works just as well as another solar controller I have for a larger setup, but is exceptionally small. It is perfect for my needs, as I have it installed in a clear faced junction box. My only concern is the temperature rating, which the spec states is up to 130 degrees F...if I remember correctly. During summer, this may be an issue. I tried to keep it in the shade and installed a small fan to assist in cooling on hot, sunny days. Time will tell if it has any issues in the middle of summer, but that is a chance I was willing to take with such a good, cheap unit. Either way I would definitely recommend this controller for smaller projects...(10 amp limit of course).