Koolance finally replied :

Hi ####,

Unfortunately, we don't specify, nor do we guarantee, a specific version of our pumps except our own SKU. While it is true that most of the PMP-400s are 3.25s, we do still have some lower versions as well.

Koolance, Inc.
Technical Support
(ph) 253-893-7551
(fx) 253-893-7573
Tech@koolance.com
www.koolance.com