It is a store bought water wand with a head that can rotate to various angles, that has been extended with an adaption. The extension in length allows you to comfortably stand upright as you spray the underside of the plants leaves with the water wand's head resting on the ground. The head is adjusted to spray upward at a nighty degree angle. This makes spraying the underside of the plants leaves so easy and really saves your back. I have used a water wand without the extension, but it is a struggle to get the wand at the right angle to spray the underside of the leaves, and you have to stoop over to get the wand up under the bottom leaves of the plant.
The piece between the brass fitting and the hose is a snap fitting that I use on all my hoses to make connecting things a snap! : )
The extension pretty much doubles the cost of the water wand (about ten dollars for the three parts bought retail.)
The water wand in use. In this picture the head is not pointing straight up. With taller plants and the head adjusted to 90 degrees you can still reach upper leaves while standing comfortably as shown.
Now the point of all this spraying is that aphids and spider mites, which reside under the leaves of your plants, are easily knocked off with a spray of water and don't seem to be smart enough to crawl back on. Spraying every couple of weeks helps to keep these populations in check.
I have also used the water wand with a partner to pick off stink bugs and cucumber beetles. One person sprays a fine mist under the leaves which causes the stink bugs to run up to the top of the leaves. The other person (not me) has the job of catching and squashing the bugs.