These basic mini keg spears allow you to hook up a liquid out hose (usually with a picnic tap or pluto gun on the end) to the barb on the side and have an M8 (metric 8mm) screw thread gas inlet for attaching a gas in hose or mini regulator directly.
They come with a 1m silicon dip tube that attaches to the barb under the unit to draw up liquid from your keg.
It is straightforward and can be used to make a low-profile tap system (using a hose clamped to the gas in thread).
They are very lightweight at only 56g so if portability is your goal they are great for that!