Thanks but I'll have to ask the contractor I paid to supply and install these. I'd be very happy to pay him to remove and return these. I can only do white as per co-op rules.

They are probably cheap “apartment building windows”.

The only return possible "may" be to him, but I doubt it. What does your contract state for the new windows? Brand? Type? Install method?

Your windows are white, that just have some black parts in them. Usually a co op is mainly concerned with outboard appearance. you did not look at the window before buying?

Missed the co-op. You may very well be locked into only certain windows as well then.

Very true. co-ops require everyone to have the same window.

If it is the jamb liner, is that something that can be changed? Thanks for your replies

Without knowing the brand and window model no, if you know all the details and the company offers the liner in white, then yes.

if they are indeed the jam line they should be able to be changed but the problem might be that they only have black ones.

I uploaded two better pictures. Can you tell me what this black part attached to the aluminum jamb is called? It runs vertical along the whole window. Thanks for all your help.

Thanks - the contractor said he'd change them and then disappeared - I've bought new curtains and blinds to hide it as much as possible