DescriptionTransparent Luxylite irregular (french) curves, set of 29, 57 1005 (old 1860S), made by Keuffel & Esser Co., no date, circa 1960-1968. Clear plastic (Luxylite); stamped markings; various shapes and sizes up to ca. 13" long. With original paper covered cardboard slipcase box, 13" x 5" x 2-1/8", with printed paper label on tray end (condition is poor with sleeve lacking a 2 x 3" section on top end; tray end opposite labeled end is loose.) For drafting and design. Individual pieces are marked: K&E; 57 1007-x[curve number]; Keuffel & Esser Co.; Luxylite. Set calls for 29 pieces, 1007-1 to 1007-30; 28 are present and the missing one is 57 1007-12. There is no curve no. 28, individually or as part of a set. In catalogue descriptions going back to the 1910s, there has not been a no. 28 in any set. No explanation is given. From 1956-1962, K&E changed over from its traditional basic product number of a four digit code (often supplemented by a letter or letters and/or a hyphenated number) to a new six digit product code. From 1956 onward (for an indefinite period), the new number and old number were often published on product sheets, labels, etc. As shown on page 198 of the 42nd edition catalog in 1954 (which is the K&E traditional depiction used for several decades), set 1860 was labeled as made of "Xylonite." "Luxylite" trademark was introduced circa 1960. Date when set 57 1005 was discontinued has not yet been found, but it was probably in the late 1960s. By 1972, it had been replaced by a 15 piece Luxylite set, 57 1006. K+E main office and factories were in Hoboken up to December 1968.