Since a picture can be worth even more than a thousand words, here's a picture of the interior of a well used SSX Turkey Choke.

Many times it's thought that the most important part of a choke tube is the exit diameter, sometimes incorrectly referred to as constriction but in reality, it's what's inside that counts.
The SSX was designed by Roger Burrell, a world champion and world record holding still target shooter. Since 2002, his design has won 9 World Championships, set 6 World Records and has made appearances in the Final Four in the World Champion Still Target Shoot Championship for 9 consecutive years, more than any other choke brand.
It just works!