Treeless saddles will come with one or the other of these.
A stirrup plate allows the position of the leathers to be altered to the riders preference. The Freeform has a movable closed ring stirrup plate allowing you to alter position of the leathers or change to an e bar.
However some treeless have fixed non removable closed ring or rings which only allow you to move between front and back. Torsion and Libra being an example.
The Dartmoor range is e bar, Barefoot Closed ring, so if this is preference of yours, its worth checking.
The Sensation has the e bar stirrup plate, it is this plate that allows those with removable closed ring plates to swap. After using both, I haven’t had any concerns with either set up. 🙂
It’s always recommended that when using a closed ring you either use a safety stirrup or the Swiss Clips Barnes buckles are still about, they just ceased trading, no reflection on the product, tested it, it works 😉