Glass lid for Pyrex measure cups?

This might be a longshot, but does anyone have a good source for a glass lid to place on top of those standard US-market 1 and 2 cup Pyrex glass measure cups? The manufacturer makes only those red silicon caps.

I use the Pyrex cups to brew tea (inelegant but functional- far easier to clean than a normal teapot, markings aid in consistency, pour off is quick with a handheld mesh strainer, and these inexpensive soda-lime versions are I believe thicker than the borosilicate cups and labware- good for heat retention).

I currently have a calphalon lid with an inner lip measurement of 6.5" that fits over the two cup perfectly (see pic) but it's discontinued so I can't find a replacement. And I need a lid with a 5.75" inner lip for the 1cup. The lids I've looked at online either don't have the inner lips or lack sufficient dimension details.

i.imgur.com