Trident 900 Airbox/carb Rubber

I have a 1994 Trident 900. Had to replace fuel pipes as they were cracking and that necessitated removal of carbs. The rubbers from airbox to carb were hard and brittle so I have replaced with new. However, the old rubbers have a metal band inside - presumably to keep the shape. The new ones don't. See pic - old on left, new on the right. Band in the middle.
Old ones had no 'cutout' to locate on the small 'pip' sticking out of the airbox, but new ones do.
Question.... I have taken the metal bands out of the old rubbers. Should I fit them in the new ones? There is a channel for them but the old ones had a section of the channel removed - presumably to make sure the band is at the right tension. Nothing like that in the new ones.
The bands are shown in the parts book, but it also looks like the part numbers for the rubbers were changed at some point.
Anyone come across this?