Hold it in your hand.. I dont have one . so let's guess.. it is made so it can change the angle.. because

unlike most stem to steerer tube shims its not one consistent wall thickness , Like I'd use with a 1" to 1 1/8" adaptation.
shim is a sleeve a tube of a thickness like 1/8" is a diameter difference between 1" & 9/8"..

Since you seem to want a shorter extension stem Go back to the shop you bought the bike from

and buy a different stem, this time get one that is not so confusingly complicated by its angle Adjustability.

Dealer should give you trade in value for the original stem .. and spend time with getting the fit more satisfactory .

I get the sense you bought a more sophisticated bike than your mechanical abilities can cope with..

Do rely on the Dealer, primarily for help as We cannot do that for You ..


I recommend reading Books on bike repair mechanics and reading several ..