Unusual types of gramophone records vinyl colors became too high, but the different colored labels were continued, at least for popular music (black) and classical (red, as in "Red Seal"). In October 1945, RCA Victor put on the market its first "non-breakable" phonograph records. Made of a ruby-red, translucent vinyl resin plastic, they cost twice as much ($2 per disc) as the 12-inch Victor Red Seal. In the 1960s, a distinction was made in label colors of promotional copies of 45 RPM records as well, with pop music being issued on yellow labels and country on light green. In the 1970s, such gimmicks started to
Lithium polymer battery the touch, they can still contain 30% to 50% liquid solvent. In this regard, how to really define what a "polymer battery" is remains an open question. Other terms used in the literature for this system include hybrid polymer electrolyte (HPE), where "hybrid" denotes the combination of the polymer matrix, the liquid solvent and the salt. It was a system like this that Bellcore used to develop an early lithium-polymer cell in 1996, which was called "plastic" lithium-ion cell (PLiON), and subsequently commercialised in 1999. A solid polymer electrolyte (SPE) is a solvent-free salt solution in a polymer medium. It