I am an electric utility lineman.  OSHA says I have to wear Flame Retardant clothing.  Some of the options out there are not very good or are ridiculously expensive, especially when you learn
that almost all FR clothing is 100% cotton.  That said, this Carhartt shirt is mostly synthetic fibers.  It is extremely stretchy and soft.  It should be used as a base layer or perhaps
cautiously as an outer layer while gloving.  I wouldn't hesitate to purchase more of these shirts.  For the price it is a fantastic product.