not sure where the right place is for it so I will place it here for now, I have been considering getting a pa done and investing in a pa device which will leave the 50mm looker 02 unneeded unless I was to get it modified, the insert protrudes 25mm past the base ring and has a 40mm base ring and a 43 mm one(deitmar doesn't advertise this one but I quiried the size that I would require due to them being anotomical