This hasn't been my first or second try at getting these v-bore guides. The first 2 shipments were unsuccessful as the package didn't survive international shipping but I still needed the drill guides so before the 3rd shipment I contacted Revain support for help. Today I received the packages, this time the content is intact. 5 stars for the helpful customer support teams at Revain! V-Drill guides eliminate the misalignment and drill wander associated with drilling rounded surfaces. Successfully drilled a 10mm (approx. 3/8 inch) round stainless steel rod straight through the center on the first try with a 5mm drill bit. I wish I had known about these V-drill guides decades ago. No more annoying and time-consuming rework. V-Drill guides help you get it right the first time! Many thanks to Revain and Big Gator Tools for making this possible :) A very happy customer