False advertising - Carlson's Choke Tubes Winchester 1200/1300 7-Round Magazine Extension

I gave a 2 star review because of false advertising.I bought what I thought was a 7 shot extension tube for a Winchester 1200. It was very easy to install. After installing I was only able to fit 5 rounds in magazine with parts sent and.... advertised as a 7 shot extension tube. I used the spring from the original magazine and got 6 rounds but not the 7 as advertised. Heads up Optics Planet product is falsely advertised by manufacturer.