Unusually, this trailer doesn't collapse in a conventional 'concertina' fashion by front to back or back to front folds. Instead, the AT3 folds down by unpinning one end of the crossbar that supports the top of the seats, then folding the sides in on each other.
The only real flaw with this fold is from stroller mode, as the push handle has to be removed before the sides will collapse. It's also when folding that the other niggle appears: the wheels are a pain to put on. They have regular quick-release skewers, but there is also a safety tab on each side that has to be fiddled with before it can be tightened. The solution is to simply leave the wheels on.
Inside there are two basic but perfectly adequate five-point harnesses, the versatility of which means that you can put two toddlers of different sizes next to each other, or one centrally placed.
On the outside, a one-piece canopy wraps from back to front over the trailer, with strategically placed Velcro fixing points to give separate access to the baggage space at the rear or the passengers at the front.
Like the Bumper, the towing arm hinges underneath the trailer and fixes out of the way. Just fix in place the single front bumper stroller wheel and you're ready to perambulate. The stroller wheel isn't articulated, and is more in the style of the Trek Go Bug Deluxe's jogging wheel. The AT3's wheelbase is considerably shorter than the Trek's though, so it's much more manoeuvrable.
The stroller kit also comes with a side pull brake that mounts on the stroller wheel. A button by the lever gives you a decent handbrake too. When you're in trailer mode the wheel can be detached with the brake attached and stowed in the rear pocket, and the handle folds down too. Adventure