He should be issued one at work. If not, check out brands like American Body Armor, Point Blank, Safariland, Second Chance or P.A.C.A. These are the most reputable vests in use today and they are not generally found in vest clearing houses like the website above.

Material like kevlar has been generally upgraded and replaced by material like SPECTRA and other fabric that is both lighter weight and more breathable as well as more penetration resistant against both high speed (bullet) and low speed (stab) projectiles.