Sanyo Denki advises 8/2015: 

Regarding our water-proof fan series, we have changed their 
model numbers in our catalog. There are no changes in either 
quality or specifications. Please refer to the model numbers 
in our catalog (model numbers appended with _U or _E). 

Parts that begin with 9WG12 an _E is added at the end. 
Parts that begin with 109W an _E is added at the end. 

Mouser stock numbers have not changed and all orders are still 
placed with the same part number.  The actual product label may 
have the _E or _U at the end of the number. 

Please contact a Mouser Technical Sales Representative for further 
information. 

5-0915-01