As it is only slightly thicker than normal civilian apparel, the CAS™ can be worn under any clothes, regardless of how thin it is. Also, it can be worn in the open as covert armor as it perfectly resembles casual clothes.
You will need to remove the ballistic panels, as they are not washable. Once they are out, it is completely possible to machine-wash the shirt and dry it as any regular clothes. Return the ballistic panel in the shirt only once it is dry.
If you need ballistic protection regularly, it would be prudent to buy multiple shirts and a single ballistic panel. That way you can wear a new clean shirt every day while not needing a dedicated panel for each one.
This product has been independently tested in NIJ-accredited laboratories according to the NIJ Standard 0101.06, as well as certified laboratories according to NATO STANAG 2920 (V50 fragmentation) and DSTU 8782:2018 against Soviet/Russian ammunition.
If you want to stay covert while adding protection against rifles, you will need to use a low-profile plate carrier like the WPC™ Weightless Plate Carrier. In such a combination, you can still wear almost any type of clothes over your armor without it being noticeable.