The description "Open End Eye" refers simply to a shock eyelet (always the "B" side) that does not have a bushing pressed in. This is a specification required to mount a shock to certain bikes especially those with Clevis-Style Mount.
A bare Open End Eye has an internal diameter of 15.02mm and a "Regular" End Eye (with bushing) has an internal diameter of 12.7mm.
***An Open End Eye shock can be made "Regular", or vice versa, by pushing a bushing in or out of the end eye.***
Open End Eye