need help identifying this part

We can supply this balance, but only as a custom order due to its configuration. Before we go any further, can you tell me the exact weight of the sash? Your stamp is fairly uncommon and I want to be 100% sure that we get you what you need. Can you also tell me the length of the metal channel? 

Once I have that data, I'll email you a purchase link and price quote that will let you place an order on our site.