WooCommerce Sale Flash Pro:
The extension helps you further incentivize sales at your store. Everyone loves a bargain but sometimes they’re hard to spot. Sale Flash Pro helps make bargains easy to find by telling the viewer exactly how much of a saving. The saving they could make on any given product available normally.
Instead of simply declaring a product is on sale, the Sale Flash Pro extension gives you global and per-product control over sale flash display. Choose whether to display the % discount or the precise amount of the price.