Sperry Instruments GFI6302 GFCI Outlet/Receptacle Tester for $5.94. Here is a screenshot for reference. Shipping is free on orders over $25. If needed, use this Filler Tool to pad the order for free shipping. It is worth noting that at the time of this post, it has received 4.4 out of 5.0 stars after 2165 reviews.