This 1000 lb. Sherline LM 1000 Trailer Tongue Scale is worth its weight in gold. WAY better than using beams, dowels, and a bathroom scale. I just put it on my floor jack and jacked it up so that it nestled into the center of the trailer tongue coupler and lifted the trailer leg off the ground. A quick check to make sure everything is leveled, a few gentle shakes on the trailer tongue to make sure the scale piston is fully settled, and VOILA: accurate tongue weight readings in less than five minutes.Why is this important? Just walking from the front to back of the boat/trailer will be eye opening as this scale shows you how significantly an average adult's body weight (~190 lbs.) can change the weight on the trailer tongue. You'll immediately see that a few hasty decisions about tossing a loaded cooler, propane tank, and some other cargo in the back of your boat/trailer can significantly alter the towing dynamics. But with a scale like this, you can just load everything up as usual and confirm the proper tongue weight before you travel. Way better than guessing.My body weight fluctuates from 185 to 195. When I first received the scale, I stepped on top and it read 190 on the nose, so it's definitely accurate to +/- 5 lbs. at least, which is plenty accurate for the intended use. When taking tongue weights, just make sure you have it centered up in the coupler, with the trailer level, and all gear/etc. loaded as you intend to tow it. The hydraulic piston can stick a little when these are new, so always wiggle the trailer a little bit to help it settle. The first two readings I took varied by 10 lbs., but once it was broken in the next five readings I took were within 3 lbs. or dead on each time, so as others noted, I think the shaft/O-rings inside may be a little stiff or dry until you operate it by placing a heavy weight on and off it a few times.Ideally, you should choose a scale with approximately twice the capacity you expect your tongue to weigh. In my case, I'm looking for a tongue weight of around 640 lbs., so I bought the 1,000-pound scale. A larger scale would be harder to read accurately (because the weight reading index marks get smaller/less precise as the capacity increases) and, more importantly, this type of scale is usually most accurate across the middle of its capacity range (i.e. roughly 250-750 lbs.) rather than at the highest or lowest ends.Keep it stored indoors, in a room temperature location, inside a plastic ziploc bag, and it should keep the fluid warm and the housing protected from rust for many years of reliable, accurate use. I can't confirm that's the case with this model, since I haven't had mine very long, but I'm pretty sure it will last if stored properly like that. It seems decently well built and I was impressed by how repeatable the readings were in use. (A few times, I took weights with a known load that I moved ten or twelve times. Each time I returned that load to the same location, I got the same reading at the tongue, which is a very good sign this scale is accurate.)In short, if you're wondering about tongue weight, this is a good investment.I put the empty 5500 lb trailer on it and got a reading of 800 lb tongue weight. I weighed it again after putting heavy items in back of the trailer and slightly loading the trailer and it was sitting at 900+ lbs. I was hoping for a tongue weight of about 10% and it appears I'm getting about 15%. I'm afraid to add a lot of weight to the back of the trailer due to possible swaying issues. I guess if you're towing something that's near the tongue capacity of your tow vehicle. This is an invaluable tool. My tow vehicle is rated for 9000 lb towing capacity but I think it's maxed out on the tongue weight capacity. Definitely need weight distribution hitch in my case.Worked as I hoped and let me know my hitch weight.Bought it to weight the tongue weight of my travel trailer. A more complex scale puts the weight at 440 lbs on the tongue jack. So I slid this scale under the jack, carefully centered it and lowered the trailer. Scale read 380 lbs. I lifted and re-lowered the trailer. 400 lbs. Again, but this time 460 lbs. Sigh. If it doesn't get better this thing will be useless.After some trial and error I found a way to overcome the significant stiction of this thing. Put the tongue jack on the scale, it reads low. Then push down on the tongue and watch the reading climb over 500. When you release the reading drops back to, say 480. Then briefly extend or retract the jack to put a bit of an impulse force into the scale. The scale jumps to 440 lbs. I did this several times in a row and got repeatable readings of 440 to 450 lbs.So, 1 star rating unless you know the trick, then it becomes 4 stars. Portability is a big plus.Ruined two bathroom scales trying to accomplishtongue weight for my trailer. This was much easierand resourceful.Toung weight on travel trailer to get the balance correct.Overall, a very handy tool to have. I'm sure my camping friends will all want to borrow it once they find out I have it. I am using it to verify that my toy hauler trailer does not exceed (or even closely approach) the maximum allowable tongue weight of my tow vehicle.There is one fairly substantive area in which it needs improvement though. The screw-in spindle that goes up into the tongue cavity is too short. It needs to be about 1/2" longer in order to reach all the way up into the trailer tongue that I have and I'm sure there are others with the same issue. At the spindle's current length, the trailer tongue flange bottoms out on the scale rim before the spindle touches the top of the tongue cavity. The only way the spindle can be used on my trailer is if I stick something up into the tongue cavity to make it less deep. Otherwise, I can only use this scale at the jack foot. I tried to put a piece of wood across the tongue opening, but there is just enough of a protrusion from the trailer frame at the back end of the tongue cavity that the wood doesn't sit perfectly level and flat across the opening. As a result, the wood didn't sit flat across the top of the scale, either. This is a great tool and a great concept, it just needs a slightly longer spindle for me to be able to use it at the most accurate place to weigh, which is at the tongue itself.UPDATE: Stoopid me, I later realized I can just unscrew the spindle a few turns to increase its effective length. Doing so, I can now lower the trailer tongue onto ONLY the tip of the spindle, with about 1/8" to spare between the tongue flange and the scale's rim. I trust the readings a bit more now, however the fact that I can get slightly different weight measurements each time proves that this is not a "dead-on accurate" device. Your readings can easily vary by +/- 50 lbs each time, so this is not recommended to use if you need to know an exact weight.