Highway Hi-Fi was a system of proprietary players and seven-inch phonograph records with standard LP center holes designed for use in automobiles. Designed and developed by Peter Goldmark, who also developed the LP microgroove, the discs utilized 135 grams of vinyl each, enough to press a then-still-standard 10-inch LP (12-inch LPs of the period commonly used 160 grams of vinyl each and 45s used roughly 70 grams).