Dynamic Inertia

a property of matter by which it remains at rest or in uniform motion in the same straight line unless acted upon by some external force but dynamically as in the Shake Weight™ product which ignites the muscles in your arms, shoulders, and chest.
Works out your arms, shoulders and chest in just 6 minutes a day

You will feel it instantly

My wife purchased the Shake Weight™ today. I could have saved the $19.95 and had her practice Dynamic Inertia on my cock.