Provides an inexpensive and efficient through bag connection for the hose to enter the vacuum bag, and lifts the bag so that the air can be drawn out through the port.  It has two grooves in its base which can have poly spiral wrap tubes laid in them to assist with good yacuum drainage.  The bag is sealed to the port and the hose using the vacuum bag sealing tape. The entrance hole is nominally 5/8"  (16mm) which makes a good tight fit with our 5/8" LDPE vacuum tube.