A holder for holding an object, comprising: a tube having a first end and a second end that is opposite to the first end; a movable clip at the first end of the tube, wherein the movable clip has an aperture through which the object can be inserted and held within the aperture; a cap at the second end of the tube; a spring inside the tube; a first retainer inside the tube, wherein the first retainer couples the movable clip to the spring; and a second retainer inside the tube, wherein the second retainer couples the cap to the spring, wherein the cap is movable to adjust a spring force of the spring for holding the object within the aperture; wherein the second retainer has a first end coupled to the cap and a second end that engages the spring; and, wherein: the spring includes a helical coil; characterized in that the second end of the second retainer has at least one tooth that extends between adjacent turns of the helical coil; and the at least one tooth is configured to travel along the helical coil when the cap is rotated, causing an increased or decreased number of turns of the helical coil to be retained by the second retainer. a tube having a first end and a second end that is opposite to the first end; a movable clip at the first end of the tube, wherein the movable clip has an aperture through which the object can be inserted and held within the aperture; a cap at the second end of the tube; a spring inside the tube; a first retainer inside the tube, wherein the first retainer couples the movable clip to the spring; and a second retainer inside the tube, wherein the second retainer couples the cap to the spring, wherein the cap is movable to adjust a spring force of the spring for holding the object within the aperture; wherein the second retainer has a first end coupled to the cap and a second end that engages the spring; and, wherein: the spring includes a helical coil; characterized in that the second end of the second retainer has at least one tooth that extends between adjacent turns of the helical coil; and the at least one tooth is configured to travel along the helical coil when the cap is rotated, causing an increased or decreased number of turns of the helical coil to be retained by the second retainer. wherein the cap is movable to adjust a spring force of the spring for holding the object within the aperture; wherein the second retainer has a first end coupled to the cap and a second end that engages the spring; and, wherein: the spring includes a helical coil; characterized in that the second end of the second retainer has at least one tooth that extends between adjacent turns of the helical coil; and the at least one tooth is configured to travel along the helical coil when the cap is rotated, causing an increased or decreased number of turns of the helical coil to be retained by the second retainer. the spring includes a helical coil; characterized in that the second end of the second retainer has at least one tooth that extends between adjacent turns of the helical coil; and the at least one tooth is configured to travel along the helical coil when the cap is rotated, causing an increased or decreased number of turns of the helical coil to be retained by the second retainer.