Easy to handle.

I'd say the 15 gal model is good product. I don't know the others. The plastic is appropriately thick and strong. The connections are good and I haven't had any leaks but for operator error. That's inevitable and you should ALWAYS have at least a couple gallons of rinse water with. It came with a sewer drain hose, female end for bayonet connection, and clamp. Assembly required. I wouldn't tow this just because towing something on wheels without bearings is just not that great an idea. But the steel tow handle is useful as a handle to pull it with by hand. It's easy to pull. All the other accessories and the stowage compartment are silly. I keep all my 'stinky' hoses and stuff in one 'stinky tub'. The built in stowage compartment and flappy door are useless wastes of capacity in my estimation. You're likely going to want to rinse bits off near the connectors because such connectors inherently leave some small bit around the gaskets. Other reviewers say you can't fully empty it. They're right. The shape could be modified to be a bit better that way. But if you keep it clean, and have a bit of rinse water to wash off any drips, it's very tidy. I haul it in the back of my Chrysler T&C and no worries about losing any spillage there. If you used the stowage compartment you'd probably have some drips from the stinky hose running down the side of the tank. Just nope on that. Dirty, stinky hoses should be kept in their own dirty stinky container.

We bought this for a 7-night stay at a water/electric site with no sewer. The dump station was a 1.5 mile round trip, so I had to pick a size that was as big as possible but still easy enough for two people to lift (when full) into the truck bed for transport. When I opened up the box I was glad I didn't buy a bigger one just due to the size and my fairly limited basement storage space in the trailer. I had been imagining something smaller, but when I stopped to think about it, yeah, 15 gallons is a lot of volume. ;)
My only complaint is that it doesn't come with a second coupling for the short sewer hose that comes with it. It comes with one, but you'll want a coupling for both ends. Luckily our new trailer came with a random spare coupling and I had some spare hose clamps that I always carry around for emergencies.
All in all it worked great and got the job done simply and easily. It's solidly built with thick plastic and beefy wheels. I was surprised how heavy it is when empty, but that's a testament to the construction. It's fairly easy to peek into the vent hole and judge the water level as you're filling. Just don't get too close or you'll get a fun wet kiss on your face if it decides to randomly sploosh out the hole while filling (as I learned while doing my first black dump into it).

My family and I used this for two week dry-camping expeditions in 2016 and 2017.

The Positives:
- It holds enough to drain a week's worth of black tank plus some gray tank, yet two male adults can lift into the car
- When it's closed up, you can't smell the contents inside. That's really important as we store it in the garage and transport inside our truck.
- Because I own it, I don't need to move my RV twice during our trip, which is a big savings in time and pain.

The Not-so-Positives:
- The hose absolutely sucks. Do yourself a favor and buy one of these: Camco 39768 RhinoFLEX 3' Tote Tank Sewer Hose Kit
- You will not get everything out of it. A little will be sloshing around. Because it doesn't smell sealed, however, I don't see a big deal.
- My unit is very low profile, so I don't get the gravity feed. It requires a bit more effort on my part, but I get it to work. Not a fault of the product -- just my situation which likely won't be the same for you.

I am glad I made the purchase. The topper is my wife is over-the-top happy because she can fill the gray and black tanks without my getting so crabby ;)

I just received the 15 gallon model, haven't had it out in the field yet. The unit is a solid plastic and the wheels look strong as well. They say you can tow it behind your tow vehicle, using the attachment. You'd have to go very slow or you're going to bounce that puppy all over the place. I plan on putting it in the back, I may have to create some kind of ramp for it.

The waste hose is a 3" diameter hose but there is only one Valterra style connector on it. The other end of the hose is just plain Jane, no attachment. That's fine because the hose is about 1.5 feet long. The video says 3' but not for this unit. I'm going to take it to my trailer in the storage lot and see how well it fits but I'll probably have to buy another length of hose for it, along with a fitting and clamp. The shorty waste hose and 1 foot wash hose with fittings will fit in the little storage compartment. Most dump stations don't have a fitting on the hose so this might be useful only at home or at the camp site.

This unit does have the metal bar carrier. It's loose, just slides under the handle then the other end has a loop to go over the hitch ball. There 's no place you can attach this carrier bar to the transport, like the larger models have. You'll have to store it someplace else and remember where you put it when the time comes.

But the unit does look solid, I think it'll fit my needs, just have to maybe modify the waste hose.