Are you certain you need an aftermarket choke tube for steel shot? The factory chokes for the 835 and 935 often pattern steel quite well, and many consider those guns to be the best right out of the box for patterning fast steel shot loads. If you haven't patterned your chokes with your loads, you might find doing so will save you some money. There's no point in spending money for a choke if it is not needed. If your shots are under 40 yards, your factory chokes should work for you. Many times, bad patterns can be cured by switching to better shells.
If you find your factory chokes don't pattern adequately with a variety of shells, then it may very well be worth the extra expense to purchase an aftermarket choke for it.