Keck ? If you clicked on this you know what I'm talking about. What's the point of them, do they protect or prevent breaking at weak points in joints?
They are used to prevent pulling the downstem up with the bowl. It happens sometimes and it's an easy way to end up with broken glass.
the keck clip keeps the downstem in the joint so that when you pull the slide the downstem will not pull out of the joint and risk breakage.
They're used hold two ground joints together. They are actually designed for scientific use in laboratories but caught on within the last few years with the scientific glass blowing trend in bongs
They are also very good for securing a mouthpiece arm to an ash catcher in order to hit it like a bubbler.