If you have a trailer you will eventually need this. Lighting issue can be much more easily diagnosed by carrying one onboard.
595704
This simple unit works great. These little testers may look like a really unneeded item but is you are having problems with trailer lighting they can be invaluable. Obviously, lighting issues may be in the tow vehicle or in the trailer. This allows you to diagnose which is the problem. Also, if your trailer is stored off-site, this let's you check your tow vehicle trailer connection before you go to pick up the trailer.
295909
Very convenient cover. I got this for our trailer that was in storage all summer. This isn't waterproof but if you take care of your trailer, this is well worth the money. I don't neglect my trailer even during times of storage so light clean up would be very beneficial. I love this cover if I weren't storing my trailer for extremely long periods of time.
1639854
This light is more visable than the orginal incandescent lights orginaly instatlled on my 1976 EZ-Loader trailer.  This was a worth while upgrade for me and everyone else on the road.
364615
arrived quickly in good packaging. bulb can break if mishandled. it was difficult to install in T10 outlet in my 2010 Jayco Jayflight 22FB...very tight fit in socket and no safe place to hold on bulb. light is very bright now in my travel trailer  thank you GRV and more cost effective than installing new fixtures. handle bulb carefully! led panel and socket are not well bonded and can bend easily at middle joint. now lights consume lots less battery power!
1462620
First one never showed up but Amazon upgraded my shipping for free on the 2nd one. UPS is the way to go.

Light is what I expected. Cord is long for my pickup truck and the magnets seem plenty strong. It's plenty bright for night time and probably adequate for daylight.

The leds are bright but small and the light is pretty concentrated, so maybe a halogen would make a larger bright spot.
269137
A bit tricky to mount if you have the "spare tire access hole" that some trucks have...but with some proper planning before drilling, that particular issue is easily overcome.
Super bright and much needed added back-up lighting in Reverse.
3462403
LED's are the way to go in RV's.  They save so much power (90% in my experience) that is usually drawn by incandescent lamps.  If you dry-camp without hookups and don't like to run a generator, you must have LEDs.  I used this one to replace the incandescent lamp in my vehicle's shower.  Good fit, good light.
4243087
Small lightweight, charge indicator light is a real big help.  I use to maintain my boat battery only for 12 hours every so often.
4370472
This was  replacement for one that seems to have cracked and failed, I lost the right turn signal after about a year. It could have been the location I chose for the module.

It does not play well with LEDs. When my trailer is plugged in and vehicle is off, my running lights glow faintly. I have had this problem with a household timer and LED's before. I just have to unplug my camper when I get to my location. This problem does not happen when my other trailer with incandescent lights is plugged in. Also, it happening on the unit I replaced.
1014738
Trailer tows very well. It is light but heavy enough not to bounce around. The length seems just right for a stable ride as well.
Instructions were very good. I would have given it a 5 star rating if it came with LED lighting. I didn't use the lights that came with it instead upgrading to LED lights.
Handles two 50 pound Kayaks without any problem.
497635
Light is plenty bright and would be useful in a closet or somewhere electricity is unavailable.  In my case I will use it in an enclosed motorcycle trailer.
It already has a light but it must be connected to the tow vehicle to work.  This swivel light (swivels 15-20 degrees) is a good solution.  The reason I only give it 3 stars is because the light comes on all by itself even when no one is in the room.  The 2 on/off press buttons are located near each end of the 4" lens and do not appear to be overly sensitive so I do not know what is making the light come on.

Full disclosure: I received this item from HisGadget free of charge to test and review.  I hope this is just a defective sample and not representative of the product.  HisGadget has sent me other items to test that have been fantastic.  At least this review should help someone
and also make readers aware that all reviews are not just hype.  My expectation is that the vendor would replace this defective item had I purchased it in the first place.

Updated 2015-10-11 @ 16:41:31: I have had this product NOT turn on by itself for about 5 days now so I don't know what's going on.  Perhaps fresh, new batteries were the cause.  Changed from 3 to 4 stars and will watch it.
1329258
I wish it came with the light itself that way i wouldnt have to buy it separately however this is useful with the light. It snaps in place and it took a lot of effort to remove them and make them separate. I don't feel like ill ever lose my tailight. It does seem sturdy and durable. Fits well with my rack as ive been having issues with other lights and rack mounts not fitting well with my rack. I recommend it along with the light as well
4437590
The company should market this marvelous light to older people. I, a 62 year old, fell in October, luckily I didn't break anything but my confidence. As the morning walk to my train stop got darker, I worried more. Then I got the light and I again feel confident.  If the company developed a holder that could be attached to a walker, elders would have a headlight to use for late night trips to the restroom. Im serious, the company should explore the senior market. I walk with confidence and my hands free. It is lightweight, it clips on easily and strongly.
782100
Having a spare battery with me is a must, I do some longer rides, keep lights on blinking during the daytime to help me be more visible and then on solid at night to help me see. I have typically stuck with the cheaper lights that use AA batteries, so I could carry a spare set, with NmHi batteries I typically get three to four weeks of daytime rides before having to swap. Having the spare battery in this makes it possible for me to head out and ride not worrying if I run out of daylight that my battery will dye before I make it home. However I do only get 2 to 3 rides instead of 3 to 4 weeks. I still haven't ridden at night time with it yet though its far brighter than my old light so I am sure I will see much better. I have never used its USB port to charge it, I already had a battery charger that is capable of charging these batteries so I just bring the dead one in after charge it up and take it back out to to my seat bag on the next ride.
It could be better, would be nice if when turning off it would restart in the mode you had it in last instead of having to cycle through modes again. but its well made and you can carry a spare battery.
194423
This trailer light set is of a very acceptable quality. Everything I needed was included and it was easy to install. The lights could be a little brighter though, but I guess you can install higher wattage bulbs if you like. Overall, very satisfied.
2876780
It works, but at the lower settings your LED lights may flicker - ours do, anyway. Still, it's great to finally have a switch at the entry to our travel trailer bedroom that allows us to turn on lights BEFORE we enter.  Price is a little high for what it is, however.
3491687
Item works well. They do put off a weird shadow but it doesn't bother me too much. I stay in my trailer about half the year dry camping so having LED lights saves my battery life. I will be ordering more to finish converting everything