Single coil

Thanks for posting. Yes, this does appear to be the 15-180 but you'll need to compare the measurements to confirm. To clip pictured next to it is the 15-186 Coil Balance Clip used along with the 15-182 Balance Bushing.

Alternate image for 15-180

This shoe is compatible with the Series 190 Coil Balance, which is secured to the shoe using the 33-073 screw.

To determine the spring strength needed for your window, you'll need to double check the coil spring for any stamps/markings. If there are none, you'll need to obtain the exact sash weight. Then you'll you'll need to take that number and divide it by the number of coils in the window.

(For example, if your window ends up weighing 12lbs, you'd need (2) 6lb coils, one for each side of the window. So you would need the S190-640.)