Offering wall, chassis, and PCB mounting accommodations, the BK-6089 holds six AA batteries in series, delivering a 9V output. It provides a sliding cover with one large snap locking tab on the front and two small tabs at the rear, allowing for quick battery changes without the use of tools.  Reverse battery protection is also built in and clear markings for battery direction are highly visible. Pricing is $2.18 each/5,000. MEMORY PROTECTION DEVICES INC., Farmingdale, NY (631) 249-0001.