Element for joining the front portion of spectacles to sidepieces for securing to the head of a user

An element for joining the front portion of spectacles to sidepieces for securing to the head of a user, the element comprising:

• a core made of a thermoplastic elastomer of vegetable origin made up of a regular linear chain of flexible polyether and rigid polyamide segments;
• and
• a coating of thermoplastic rubber, where the element has a first end face and a second end face which, with the element in a state of rest, form between them an angle defined within the range of 50° and 80°, such that starting from the first end face, the element has a first side of the element with a first curved portion with a first radius that provides a concave section to the element, up to a second curved portion, of opposite curvature to the first curved portion that connects with a first flat portion that is perpendicular to the second end face;
• and a second side of the element, opposite to the first side, has a third curved portion with a second radius that provides a concave section to the element, then a second flat portion that reaches the first end face perpendicularly.