locating pins 154 may protrude directly from the securement blocks 106 without the need for a lockbar 153 in some embodiments the fastening means 152 may be a clamp a clip a bracket a band a magnet or any other fastener that can reversibly fasten the securement block 106 to the base 102 while immobilizing the first and second sides 122 and 124 relative to each other for example the fastener 152 may be a c shaped clamp or bracket type device that clamps or fits around the outer edges of the first and second sides 122 and 124 in such embodiments the holes 126 would not be required on the first and second sides 122 and 124 and the securement block 106 could slide along the base 102 to be placed in the desired position in use the holder 100 is passed along the backrest 10 so that the headrest rod 14 is passed through the opening 114 into the gap 118 to the desired position once the holder 100 is in position at least one securement block 106 is inserted in between the holder 100 and the headrest 12 that is supported by the headrest rod 14 preferably the securement block 106 is positioned adjacent to the headrest rod 14 so that the securement block 106 prevents movement in at least one direction the securement block 106 may be placed below the holder 100 between the holder 100 and the backrest 10 or above the holder 100 between the holder 100 and the headrest 12 in some embodiments two or more securement blocks 106 and 106 u2032 may be utilized in a variety of configurations to secure the holder 100 for example two securement.