Snap Glazing for Mayfair window

Hello. I'm trying to find this snap glazing for our windows. From what I can tell, the face of the existing glazing is 1/2" and the seat portion is 3/8". The color is white. The window manufacturer is Mayfair and the model is Classic. All of the windows on my entire home have this glazing, and all of them need some repair so I have no idea how much material I will need but it will be a lot. First, I need to determine what will work and then place an order. Thanks for your help.

-Ryan