Chemistry - What are the plastic connectors called (for glassware)?

Solution 1:

Those are called Keck Clips. 24/40 is the size of the joint.

Solution 2:

They are called Keck clamps.

Here's a link to the page for ChemGlass: http://www.chemglass.com/product_view.asp?pnr=CG-145

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Solution 3:

The clips are named after Hermann Keck - Chemistry World's Classic Kit columnist, Andrea Sella, spoke to him to get the story of the invention before he died a few years ago. https://www.chemistryworld.com/opinion/classic-kit-keck-clip/3004921.article