The clamp looks well crafted.The gooseneck is really easy to bend and place it at any angle you wish.I bought it for my Audio technica pro 70 and it fits perfectly.The gooseneck length though could be a little longer.
Now be careful.If you buy this clamp in order to mount it on a guitar,be sure your guitar has a suitable spot.There are probably a lot of places INSIDE the guitar body where you can mount the clamp,but it seems there are not too many on the outside.The guitar bridge might be such a spot and MAYBE the guitar soundhole another.
I also have to comment on the price.In my opinion,the AT 8418 is just too expensive.I bought it because I wanted to be sure the clamp would fit my AT mic,but you could probably get away with a cheaper solution.