The surface of the Rumble Roller contains specially designed "bumps" that are firm but flexible, much like the thumbs of a massage therapist.
 
The bumps are firmer than muscle tissue, but much softer than bone, so they deflect out of the way if they contact your spine or other bony protrusions.
 
As you roll on the RumbleRoller, the bumps continuously knead the contours of your body, stretching soft tissue in multiple directions to help restore flexibility and bring relief to common types of muscular pain.
 
The RumbleRoller is waterproof and is also molded with an antimicrobial additive that stops the growth of bacteria.

The extra firm density of this RumbleRoller provides even deeper massage and tension release than the RumbleRoller Firm, making it a great choice for athletes or those with very dense muscle tissue.  
 
Available in two sizes: Full 31" L x 6" diameter or Portable 12” L x 5” diameter
 
Caution: Aggressive use may cause minor bruising.