Reporting question for Vacuum Tube - 5881WXT, Sovtek

Product:
Vacuum Tube - 5881WXT, Sovtek

Question:
In the description, it says "Built to rigid military standards, the 5881 will tolerate higher voltages than any other 6L6." Then later, it says "max plate voltage is 250V. Other 6l6s are rated for 500 plate volts. This doesn't make any sense. Please explain. Thank you.