lrtraut

Though I'm not familiar with that particular model and am not an expert, I will try to explain some basics. If it has a fixed cylinder choke, that indicates that the choke is "fixed" and not interchangeable. The choke is referring to a taper of the inner diameter of the barrel at the muzzle thataffects the shot pattern. A cylinder bore choke is essentially the same diameter as the bore and would have a "wider" pattern, while a modified or full choke will have a "tighter" pattern because the diameter is smaller ot "tighter". Typically tactical shotguns use a cylinder or improved cylinder choke. Hope this helps.

Factory Benelli M1 Super 90 mag extension with barrel clamp, sling swivel and spring. It gives you 7+1 capacity with 2 3/4" shells. SOLD

Looks to me like a factory benelli mag tube extension and should give you a 7+1 capacity. The followers are readily available and you can find aftermarket aluminum ones.