The apotheosis of the twist lock clutch. This is a very excellent pencil, but it was late on the scene (1945) and so had to compete against the much more convenient pushbutton clutch leadholders popularized in the U.S. by A.W. Faber's Locktite in the late 1940s and widely copied by other manufacturers soon after. This is one of the few leadholders of a quality and refinement comparable with other top quality drafting tools. The only other drafting leadholder I am aware of that also uses a compression washer clutch is the Bruning 3583.

I suspect the inventor of the Elastichuck, James C. Winslow, was surprised to find that his concept had been used a few years earlier by Alfred Jeffries in US Patent 460,971 in 1891, and possibly even earlier. This pencil does have a Design Patent which is more like a copyright on the specifics of the pencil's appearance. A design patent really is somewhat of a joke—you could change some superficial aspect of the pencil's appearance and manufacture and market them with impunity.

One very unique and useful feature of this double ended pencil is its ability to accept a full length (5 inch) stick of graphite in each end simultaneously. The large hollow of the barrel and the give of the rubber washer clutch allow the leads to bypass each other. This is the only double ender I know of in which this is possible.