4 to 3 pin y cable (for fans)

Solution
The connectors have a "slider" right behind th pins that are the ones to use. The cable connector has a notch in them as well that fit that slider on the connector.
I myself have not seen thorse. But you really dont need them either. The 3 pin cables fit the 4pin connectors. I'd just go for normal 3 pin splitters and save the hazzle of finding something that might not exist.
 


If I use a 3 pin y splitter cable, one pin on the MOBO will be sticking out. Should that pin be the right most or the left most one on the fan connector?