Rotary trimmer apparatus and related rotary head assembly

An apparatus comprising

• a rotary head assembly configured for attachment to a rotary power source, the rotary head assembly comprising
• a rotary head housing defining
• one or more slots, each of the slots being intersected by at least a portion of a respective retention member chamber defined by the rotary head housing, and each of the slots being sized and configured to receive a respective retained member
• a first face and a second face, wherein the first face and the respective retention member chamber define a respective first face aperture;
• one or more retention members, each comprising a first retention member portion and a second retention member portion, wherein the second retention member portion is sized and configured such that at least a portion of the second retention member portion may be disposed within a respective retention member chamber;
• and
• one or more biasing members, each biasing member and a respective one of the retention members being coupled to the rotary head housing and each biasing member biasing the respective retention member so that (i) the first retention member portion extends through the respective first face aperture and is external of the respective retention member chamber such that the first retention member portion is accessible to manipulation by an actuating external force and (ii) the second retention member portion thereof in the respective retention member chamber intersects and extends through the respective slot, thereby retaining a portion of the retained member within the respective slot,
• wherein each retention member and respective biasing member are sized and configured so that, when the actuating external force is applied to the first retention member portion, the retention member is actuated causing the bias of the biasing member to be overcome and the second retention member portion to be removed from the respective slot, thereby releasing the respective retained member from the respective slot;
• and
• wherein at least a portion of the second retention member portion is geometrically shaped, and an aperture defined by the retained member is defined in a geometrical mating fashion relative to the geometrically shaped second retention member portion, so that the second retention member portion is removed from the aperture defined by the retained member through which the second retention member portion extends only when the second retention member portion is in key-and-lock style geometric alignment with the aperture defined by the retained member.