The LH0538 HH Fluorescent 1-526RW-2 is a "V" lock tombstone /lampholder / socket. It is for G13 medium base bipin fluorescent or LED bulbs. the LH0538 HH Fluorescent 1-526RW-2 comes with nut inserted and is designed to be screw mounted.
Link to T8,T10,T12,lamps that fit this socket