Most foam rollers are a hollow tube in a foam sleeve.
Lean your full weight on one and it flexes, and the pressure you were after never reaches the muscle. This one is solid EVA all the way through, so it pushes back.
The raised blocks concentrate the pressure into narrow lines instead of spreading it flat, which is what you want on a tight IT band or the length of your spine. The 60 cm covers your whole back across the grain; the 45 cm fits in a gym bag.
Uncomfortable on purpose.
Specifications
Lengths: 60 cm and 45 cm
Diameter: 13 cm
Material: solid-core EVA foam, no inner tube
Surface hardness: 75° Shore
Textured block surface, black
In the box
Foam roller × 1
NO GRRIT, NO GLORY.


