Very simple and cheap to manufacture.
- Doublethreaded trapezoid screw with 6mm pitch is used for on/off in single turn. Screw is dimensioned for any step on force. Friction coefficient is enough to keep position, or to add some rubber friction element.
- Upper cover is positioned at the top by vulcanized rubber that is secure element for eventually step on.
- Material is stainless steel AISI316L for long lasting at sea.
- Doublethreade nut is Al-bronze, or SI-bronze.