Need coil system hardware for window

Welcome to SWISCO. Let's begin with your coil and go from there. Our Series 190 is worth considering. Since you mentioned there are no numbers or markings on the spring itself, you will need to weigh the sash and get back to us with the weight number. Should you also need the accessories that accompany the spring, we placed a list of related items for you to look at on this page. Just be sure as you look at each item that you are matching up your measurements with ours. 

Yes, you do because that information does not give us the weight.

Thank you for the additional information. You can use two of the S190-540 coil springs on each side of the window to help hold up your sash. For two coils, you would also want to use the 15-181 double support detent clip. Look over the parts and let us know if you have any other questions.