Stepless fastening device

A stepless fastening device comprising:

• a cap having a driving gear connected to an underside thereof and multiple one-direction teeth located around the driving gear;
• an operation unit located beneath the cap and including an operation ring, an activation ring and an engaging member;
• the operation ring of the operation unit including multiple pressing blocks located on an underside thereof and each pressing block including an inclined surface;
• the activation ring further comprising a skirt, multiple notches and multiple protrusions, the skirt extending from an underside of the activation ring and the multiple notches defined in an outer periphery of the activation ring, the protrusions extending from a top of the activation ring and the pressing blocks contacting the protrusions of the activation ring, the activation ring being located in the operation ring;
• a base having a spool which has teeth engaged with the driving gear of the cap, and
• the operation unit being rotatable in a first direction to rotate the spool in the same direction for tightening a shoelace, the operation unit being rotatable in a second direction to rotate the spool in the same direction for loosening the shoelace.