After the wild success of the 51 throughout the 1940’s and 50’s, Parker was ready for change by the late 50’s. Their changes were in three major directions — new technology and efficiency with the capillary filling 61, economy with the 51-“lite” 21, and a bit of all of it in the all-new 45. The 45 (yes, named for the revolver that “won the west”) and following the design of Eversharp's 10,000 which was owned by Parker by this time, revolutionized pen manufacture by introducing refillable and replaceable cartridges and continuing hooded nibs, now with plastic feeds. The 45 Classic had a brushed steel cap, gold-plated clip and cap ring, and a plastic body and section that was available in numerous colors. In addition, they were all one size, 5 3/8” long capped, longer and slimmer than 51’s and 21’s, with both ends tapered.
In 1960-61, Parker produced a variety of derivative 45s, perhaps to settle into the 45 form, including the 17, 19, and the Eversharp Big E. These were inexpensive plastic pens, with metal clips, crowns, and a something like a clutch ring. Their plastic was polystyrene, so soft; they used Parker cartridges; but like the 45s they resembled, were excellent writers.