Ok guys I really couldn't find anything out there where the how's and why of the popular styles was discussed. I've now done some trial and error testing on my own. Three models I've tested were the vortex standard, vortex uni ( Jim white), and the field optics. I'll post up some low quality pictures( sorry) comparing the uni and field optics (fo). The standard is pretty straight forward it must be removed each time if binoculars are to be worn. The standard did fit in my slick 707 head without an adaptor through.