ASC tube trap: which's reflect or absorb side?

The silver button indicates the reflective side as correctly stated by Fmpnd. However, if these are original ASC tube traps & well maintained then there should be a sticker on one of the end caps that clearly states which hemisphere is absorptive & which is reflective. FWIW.

Yes, mine have a silver button. So, the side that has silver button is reflective side.
Thanks for your help!
Tran

Ramses' answer is my recollection with my old tube traps, which did not have the button Fmpnd mentions.

the side that is vertically stitched is the midpoint of the totally absorbtive side

Do your traps have a small silver button (maybe 1/8 to 1/4" in diameter) on the bottom at any point? If so, that is the middle of the reflective side as I understand it. I have the Super Traps and this is how mine are.