Balancer

Thanks for reaching out to us! This appears to be the Series 795 channel balance but with the 15-195B open-cam shoe which is sold separately. The video below will show you how to swap the shoes out. I can't determine the length of your balance from this photo, however. You would need to measure the metal channel and weigh the window sash on a scale in order to pick out the proper length and spring strength option. 

If you have any questions just let us know!