To allow use of our front add-on parts with an older style fast-up rear system or other fast-up rear air system. Includes tee union to tap into your high pressure airline, straight and 90° fitting and plug for manifold inlet, straight fitting for manifold output, high pressure airline and manifold bolts. Default tee union and inlet fitting size is 1/4" o.d., default outlet fitting size is 5/32" o.d., if you have a different size high pressure airline please note that and we can send either 5/32" or 1/8" instead.