spindle adaptors - usually a round column that you would place on the center spindle of your record player, which allowed you to play 45's - which had a larger hole in the middle (instead of LPs which had a small hole in the middle). Sometimes you used a
45 plastic insert in the hole which was an odd-shaped piece of plastic.
45's, LP's, and 78's - refers to the revolutions per minute that a musical record makes around the player. 45's were the equivalent of today's single CD recordings...