A trimmer head for a string trimmer mower, including a trimmer head housing having a string retention portion and a coupler portion rotatably attached to the string retention portion, the string retention portion having a first string retainer for releasably retaining a first cutting string. In addition, the string retention portion has a second string retainer for releasably retaining a second cutting string. The second string retainer is preferably circumferentially displaced on the string retention portion from the first string retainer. In a preferred embodiment, the first string retainer has a slidable clamp disposed in the interior and accessible from the exterior. The clamp is constructed and arranged for sliding relative to the base between a clamping position for selectively retaining the string in place through centrifugal force in the string retention portion, and a release position for user replacement of the first cutting string without tools.