Self-Seal Computer Cheque Envelope compatibility with cheques?

From the Services -> Cheques and Forms menu, Sage 50 send me here as an option to order self-sealing cheque envelopes: D+H business cheques. However, almost no details are given about the measurements of the windows on the envelope. Does anyone know how I'm able to verify the compatibility between these envelopes and the cheques we have from Sage before purchasing them?