Some thirsty plants require more water than others. If you use the Rain8 2-Way X10 Sprinkler Controller to manage your sprinkler system remotely or via X10 commands, you can expand the system to additional zones of your landscaping for more targeted watering. The Rain8II 8-Zone Expansion Module allows remote sprinkler control of an additional eight zones; this system allows you to create up to 256 zones total. The Rain8 2-Way X10 Sprinkler Controller is sold separately. By linking your sprinklers to your X10 system, you'll be able to program your watering schedule on your computer's monitor and start the sprinklers at the push of a button, just like any other X10 appliance. Thanks to the included modular splitter, up to two Rain8II 8-Zone Expansion Modules can connect to a single PowerLinc or TW523 to communicate from your computer through the powerlines; both are sold separately. If you plan to create more than 16 zones, you'll want to add a RJ45 Splitter for PowerLinc Interface: This splitter is available for X10-controlled installations of up to 40 zones.