Upper control arm bushing extra part?

In a lot of the kits, you get that part, but it's made of poly. The reason for those is for control arms like on GM cars where the bushing presses through two holes on each side of the arm. You install the bushing in the first half, slide the sleeve on then press the bushing the rest of the way in. The sleeve fits between both sides of the control arm and acts as a support so the arm is not crushed when using a press.