Building a wider rig? The 4-way Y-splitter fans one driver out to four separate Flex II chains. It pairs with the 150W, 240W and 320W Flex II drivers. You get a WDC21 male plug feeding four WDC19 female sockets, the main lead at 105 cm and the branches between 15 and 30 cm.
This is what turns a single driver into power for a full multi-shelf propagation rack.