I have used the LAPump 1.5 inch wide mouth. It’s base measures 1.5 x 1.75 so it’s “diameter” is between 1.5 and 1.75 in an equivalent round cylinder or about 1.65”. I believe the Vacutech wide mouth 1.5 has a base of 1.5 x 2 so it accommodates a larger girth than the LAPump.
Accordingly,the 1.75 LAP would have a base measurement of 1.75 X 2 which would have a “diameter” of about 1.9 equivalent in a round size.