These are JES Model 31-55-BH1
2 Pole 450V Gas Discharge Surge Protector Tube
with pre-bent and trimmed axial leads

6.76mm wide x 8mm diameter
Overall length with leads: 27.8mm

These items have leads bent and trimmed for board insertion.

See 1000 Volt Siemens version at Press Send at https://www.ebay.com/itm/250996680542

These are factory new parts. They have never been installed and have not been recovered from manufactured electronic components.