https://www.ebay.com/sch/i.html?_nkw=3M+Low+Pressure+Dual+Airline+Back+Mounted+Adapter+Kit&_sacat=0&_dmd=2

3M Low Pressure Dual Airline Back-Mounted Adapter Kit

Regular price
$296.00
Sale price
$209.00

Low Pressure Dual Airline Back-Mounted Adapter Kit, For Use With 7000 Series, 6000 Series, and FF-400 Series Full face Respirators, Includes Breathing Tube, Waist Belt and Regulator