Product Description : Balancefrom Ab Mat Trainer Abdominal Machine Exercise Crunch Roller Workout Exerciser Overview: An Ab Mat Is A Simple Way To Increase The Effectiveness Of Your Old Fashioned Sit-Ups By About 100% This Arch Is Designed For Your Lower Back So When You Perform A Sit Up Over It, It Supports Your Spin Through The Movement Causing You To Utilize The Full Range Of Motion In Your Abs This Requires More Effort To Do, Making It A More Effective Workoutdimensions: 2 Sizes To Choose From According To Your Needs 15 X 12 X 2 And 10 X 12 X 2At A Glance:Optimized Density - The Mat Is Neither Too Hard Or Soft For Better And Comfortable Workoutcontoured - Designed To Fit The Lower Back For Optimal Comfort And Lumbar Supportlightweight - Light Weight For Easy Storage And Transportation, Take It For Your Gym Exercise