Massage your muscles easily before or after a workout with the Triggerpoint The Grid STK. You grasp the roller with both hands and roll it over your muscles to stimulate your blood circulation. This warms your muscles and prevents muscle pain. The Grid STK has different surfaces with which you can put pressure in different ways and relieve your muscles. The difference between The Grid STK and The Grid STK X is in the solidity of the roller. The Grid STK X is slightly firmer so you can put more pressure.