Insecticidal phenylalkyl substituted dihydrobenzofuran and dihydrobenzopyran derivatives of Formula I are disclosed. The enclosure body includes a bottom panel, a rear panel substantially perpendicular to the bottom panel, and a side panel substantially perpendicular to the bottom panel and the rear panel. Further, the ROM is formed with a positioning protrusion, and the holding portion is formed with a receiving hole into which the positioning protrusion is aligned and fitted. With this heat treatment, the nickel elements are diffused in the amorphous silicon film, thereby being capable of lowering the concentration of nickel in the crystallized silicon film. The timing based servo track then allows for the precise alignment of data read heads based on the positional information obtained by a servo read head which scans the continuously variable servo track.