This is a curved mouthpiece with an upward and forward bend, two hinges and a centre piece with barrel that acts as the fixing point for the two independent side movement  parts of the bit that wrap the bars and lips of the horses mouth. There's no restriction in degree of collapse. This offers lots of tongue relief to the compliant horse but will put downward pressure on top of bars when activated, followed by downward pressure on tongue and inward collapse on bars.

This bit can also work well for a strong horse with its head carriage behind the bridle. 

With the right forward driving leg aids the bit encourages the horse up into bridle.