Volatile impregnated substrates, such as wicks and mats, that can be used in a dispensing device that uses a heat source or otherwise uses active means to promote the release of the volatile material from the substrate are disclosed. A demarcation module demarks a parity data block in each set of a specified number of data blocks on a hard disk drive. The control member has a second engaging area removably engaged with the first engaging area along the longitudinal direction of the transverse hole.