The LH0003 (HH 1-726W) is a tombstone socket medium bipin (G13) lamp holder, it is flush mount with an untapped center hole. The 1-726W is non-shunted and a butt on mounting type.  the LH0003 H.H. Fluorescent 1-726W is comparable or equal to the ALP 208, DM: Y68-9, 85614, Golo SC600 and ...