Advance’s Boundless is a harness and rucksack combined, but it does not reverse. Instead, the zipped-on rucksack with its padding folds away underneath the harness seat, where it is an integral part of the certified protection system.
Advance say the system is easier than reversing the harness, and has the advantage that, because the bag stows under the seat, there is more room in the back compartment to carry things.
Alternatively, the rucksack padding can be separated from the bag and just the padding stowed under the seat (this is essential for the certification to be valid). The rucksack can then be stored in the harness back compartment.

The Boundless protector system comprises an air-foam element, a foam element and the rucksack with its built-in back foam
The harness is sleek with a compact seat board, and Advance say it is easy to get into and out of for take-off and landing. It weighs 3.8kg to 4.10kg across the three sizes, and is suitable as a first harness and ideal for hike-and-fly, thermalling and travel.