daddarrio nickle bronze 11,s .. i have an f412 ,and they have that guitar singing .We are hanging out with my wife's 2 best friends out in Hampton Bays on Long Island this weekend. I am bringing my 412 and plan to visit the local guitar shop and purchase a set of strings and then change them while the girls do their thing. I've always used D'Addario Phosphor Bronze lights. Maybe I will be adventurous and try something new!