RB21p 1/4 cent proprietary full sheet of 200
So while the sheet is remarkable just because it exists, it contains an HH14 example, or the hyphen hole perforation variety in which the perforations appear as 14 perfs per 2 centimeters rather than 7. The cause of this variety is explained in this post. Thanks to JW Palmer for his elegant explanation of this anomaly.
In the Ebay listing is included this closeup scan:
The bottom rows of stamps clearly show the HH14 variety. Below is an even closer view:
Thanks to Dave T for spotting the HH14s in the sheet!