K-Line's Super K and Supersnap are virtually identical with the exception of the added connector piece on the Snap (it can be removed to mate with Super K and Lionel's tubular track & switches). Don't confuse these with Super O, which is Lionel's postwar offering and has a very different way of connecting sections to each other. The tightest curves for Super K track are 031 and 042 radii.
IMO a great product, a shame it's not produced anymore. Mates beautifully with Lionel 022 switches and operating tracks. There is a company named "O-Line Reproductions" that makes SuperSnap switches and crossovers; you can find them on ebay.