Muscles worked:  Chest, Triceps, Trapezius, Biceps, Abdominals
Suggested resistance setting: 2-3 for Dip, 4-6 for Ab Crunch

Dip:  Grasp handles, push & pull in quick, smooth motions. 
Ab Crunch:  Extend legs out straight, grasp handles, lock elbows, crunch forward in a limited range of motion keeping arms straight.