Sparkomatic Stereo Cassette Adaptor. Play any cassette in your 8 track player. Model SCA10. New old stock in original box. Box has wear on all edges and remainder of a retail store sticker on front. Inside new with styrofoam and original instructions. Has original vinyl sleeve protector but due to age it has split and cracked.  Can still slide in but not fully effective anymore. 

Rest is just as new as it was on the shelf. 

Locking fast forward, play and stop - 3 function features.