Hakko Heavy Duty Air Manifolds are designed specifically to reduce back-pressure on your air pump. The brass manifolds connect to the pump via a 3/4" barb. This 3/4" barb is threaded on the back, allowing for adjustment, and is easily connected to the Hakko L-tube. We strongly recommend that you have at least one valve more than is needed. Keep the extra valve open when starting the pump and slowly close the valve until the desired air volume is flowing through each of the other open valves. In this way, you can protect your air pump by preventing excessive back pressure.
These valves are very well-made and meet an important need — no matter what brand air pump you plan to use!
(NOTE: On the 3/4" Barbs. They are a TRUE 3/4" (12/16" on a ruler). Most plastic barbs and pipe that are titled 3?4" are actually 13/16", therefore the Matala 3/4" barbed fitting may fit a little loosely inside your 3/4" poly or flexible PVC pipe. We still recommend this high quality item. The solution is too wrap the barb with layer of black electrical or duct tape before inserting in the tubing. This will allow for a good tight seal.