T6 - Trapeze, closed quicklink of stainless steel by Peguet company:
- work load up to 450 kg,
- breaking load: 2250 kg
- fits risers of 20-25 / 30-35 mm width
Trapeze is used for example to attach V-riser to the harness. Of course you can use squares for that too - all depends on actual set (especially width of the risers and harness straps).