Set up to take the 12 gram in the front of the bottom tube instead of in the vertical position. Also has a Palmer Sight Hood.
None. Well, the sight hood is nice so maybe that.
It is excellent. Very accurate, very efficient (30-40 shots off 1 12 gram) Handbuilt to excellent standards, very solid. If you know anything about Palmers, you know what sort of quality is built into this gun. Durable, good looking nickle plated finish, match honed brass barrel that Palmers is famous for (very accurate), and overall quality construction and feel.
Not a thing.
If you have the means and are an avid stock class player you can't beat this gun for stock class play. It and a VSC Phantom are tied in my oppinion for the best stock class guns available (have yet to play with a Carter)