At first glance, it appears to be a "Evolution Upgrade".
No qualms over Theo. "rammers", been using them for pest control, culling and hunting operations for 20 years or so. No particular interest in "techie stuff" as long as they perform in the field in all weathers, all mine have and I still use two Fenman one of which goes back to the mid ninties.
See its only available in a right handed stock though ?.... great.