 They can be used. We have these special ballistic T-shirts that have pockets on the inside of the T-shirts that they fit perfectly in the T-shirt. These shirts are great for people who might do security detail, who might be part of their church security team, something like that, who want a little protection, but yet it's easily concealed. If you put like a sweatshirt or if you put a overcoat or sport jacket over top,