Not sure if this is much of a deal...seems like on. I just picked up a 20 this year but...
Midway has the Carlson 20ga Rem choke .575 on sale right now for $19.99.
https://www.midwayusa.com/product/785016/carlsons-extended-turkey-choke-tube-remington-rem-choke-20-gauge-575-constriction (https://www.midwayusa.com/product/785016/carlsons-extended-turkey-choke-tube-remington-rem-choke-20-gauge-575-constriction)
I heard these for the most part have good reviews with the Fed HW 7's.
Great choke. Fine price. I have the non ported version, & love it