Trying on A Suit not Checked for Shaatnez

Trying on a Garment Not Checked for Shatnez

The Torah forbids us to wear a garment that contains both wool and linen, which is called kilayim, or shatnez. But is it permissible to put on a garment that has not been checked for shatnez for the purpose of modeling it for customers, for example? There is a difference of opinion among poskim whether this is permissible. However, all poskim agree that ha’tznu’im nimna’im, modest, upright, G-d fearing people should avoid doing so. 

What is the halachah regarding trying on a suit in a store to see whether it fits well? Some say that even those poskim who permit trying on an unchecked garment for the purpose of selling it, do not permit trying one on when shopping. However, the common custom is that we do try on clothing that have not been checked for shatnez. There are two reasons for this leniency: It is not definite that the garment contains shatnez, just a possibility, as many do not, and even if it indeed contains shatnez, it may be shatnez derabbonon (shatnez which is only forbidden rabbinically). Poskim say that trying on a garment for the purpose of alterations is not a problem.  #279?1 

https://halacha2go.com?number=279

Practical Halacha: One minute a day. By Horav Yosef Yeshaya Braun, shlita, Mara D'asra and member of the Badatz of Crown Heights.