490 V Clamping Volt On MOV Surge Protector: Seems Very High; Is It ?

Hello,
Thinking of installing an Intermatic AG series surge protector across a single 110 V line to help protect a circuiit board in a furnace.
This would be a modelAG2401
Clamping voltage is given as 490 V.
Seems awfully high.
Wouldn't most solid state devices such as PC circuit boards uprocessors, etc. blow (well) before this level ?
Know of any similar point of service wired in units with a lower clamping volt. ?
As always, much thanks for help and info; really appreciate it, B.
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