Theses are genuine Fender parts at a nice price, and the're a great (& simple) upgrade for your guitar - What's not to like? I fitted two of these to my Mex. Stratocaster. It was already fitted with a butterfly-type string tree, but I wanted a more professional look. I used the fixing hole frfom the existing string tree as my starting point. These trees have an anti-rotation nib which needs to be located in a small diameter hole. After aligning the tree to the loosened strings, I partly screwed the string tree down which allowed the nib to mark its own position. If you don't have a drill small enough for the job, or are unsure about drilling into the headstock, use a Bradawl to make a small hole by hand - Bradawl is £1.99 from Screwfix. Finally screw the tree down to the headstock, and admire your 'Am. Standard' string tree arrangement!