Commanders have a 4 1/4 inch barrel and have an alloy frame now designated the LW "light weight" Commanders , Combat Commanders are steel or stainless steel framed still with the 4 1/4 barrels . Officers Models have a 3 1/2 in barrel .
I think but am not sure they also made 1911 platform guns with an even 3 in barrel but not positive what their designation was .