Trimble back for Ulster as Sarries sign up Gaffney
Trimble, 21, who has agreed a three-year contract but has yet to put pen to paper, returns for his first start for second-placed Ulster since February 17 due to his Ireland duty.
He takes over in the centre from Paul Steinmetz who picked up a fractured cheekbone in that Dragon's game. Trimble joins veteran Jonny Bell in midfield.