Frequency Controller - WDFC450-4 WorldWide Electric Sale! from 896550 949000 /per Qty. Add to Cart This item is currently on backorder but you can still purchase it now and we'll ship as soon as more become available. WorldWide Variable Frequency Drives - WorldDrive Flex Control - The WDFC - WDFC450-4 with 24 hour support and technical training. Tweet