2 Singer Tension check springs.  Part# 125316 .  Genuine Singer Replacement Part . Best Spring you can buy. Will not Break or lose shape as easily as other cheaper springs being sold . 

Will Fit Singer Models

15-125, 15-18, 15-210, 15-211, 15-75, 15-88, 15-89, 15-90, 15-91, 15K88, 15K91