This is a channel balance for a Gapco non-tilt window. There is a number stamped on the balance b3340
Paul from SWISCO responded:
February 7, 2017
It's hard to tell what you have. An important feature is the bottom shoe, but I can't make yours out. Could our Series 395 be a good match? Look it over and see what you think.
A handy person from Chicago says:
February 7, 2017
After reviewing dimensions and top/bottom shoes, I determined the series 395 was correct. I have ordered a pair