PA509A#ABA refers to theHP External USB 2.0 MultiBay II Cradle, an accessory for olderCompaqMobile Workstations like the nw8240, designed to hold and provide external USB 2.0 access for optical drives (CD/DVD) or hard drives that fit into HP's MultiBay II standard. It allows you to add storage or optical drives to laptops externallyI have 23 pieces in stock brand new never used used old stock. Let me know if you want to make a "Take All" offerKit includes361297-001 HP External DVD-RW MultiBay Optical Drive281853-002 USB-mini 6-Pin Cable365661-001 Multibay USB External Cable367044-001 HSTNN-P05A 5v 3.6a AC AdapterInput Voltage 100-240VAC 50/60HzDoc Set