Interesting. It appears to be wider than the 73303.
I measured the Mirtone 73303 to be about 2-3/4” x 4-1/2”. The Mirtone MS-400, which I was told replaces the 73303, is 3-1/2" x 4-1/2". So it is 3/4" wider.
I wonder if the size for this style of pull station is standardized across different brands.