An integrated circuit including a multiplexer circuit and numerous memory cells are coupled to one another for improved performance. A hard disk drive 7 is placed in the hard disk case 6. A controller receives a feedback signal for generating a first switching signal and a second switching signal coupled to drive the first transistor and the second transistor respectively. The polarization axes of the first and second wedges are substantially parallel to the direction of predominant polarization of the illuminating beam. The outer pouch is sprayed on the inside with odour control compound to mitigate the faecal odour. More than one tab may be employed at the ends of the sleeve, and the tabs may have defined spacing andor dimensions to enable security keying, only permitting coupling between connectors possessing matching holes in the ferrule barrels.