This pump appears to have the hose barbs OD 5/8” which is in add as only 1/2 and 3/4 are listed. the sticker. https://www.pumpvendor.com/media/laing/Laing_D5_Series.pdf Technical data Motor design Electronically commutated spherical motor with permanent magnet rotor/impeller Voltage 8 - 25 Volt Power consumption see pump curves Current draw D5basic and vario: 0.25 – 1.46 A D5strong: 0.13 - 2.1 A Acceptable media domestic hot water, water/glycol mixtures, other media on request*. Insulation class IP 42 / Class F 50 PSI - 0.35 MPa (3.5 bar) for pumps with plastic housing