The AD King Exercise Machine (often referred to as an Ab King or ADKING adjustable bench) is a versatile, foldable home workout station. It is primarily used for core training (sit-ups and crunches), but can also be adjusted into an incline/decline weight bench for a full-body workout.Core ExercisesBasic Crunches: Set the bench to a flat or slight decline, rest your neck and back on the pad, and use your abdominal muscles to lift your upper body, contracting your core fully.