Help with Identifying ring

[EC.Mason]

Hello all, I found this silver ring at my great grandfathers house. It says "silver filled esp. on the inside, but I cant find any additional information on the ring. Id love to find roughly what decade its from. Anyone seen a ring like this or have some information to help? Thanks for looking!

 

[Sentrom]

Could the ESP be ESPO? If it is, ESPO is a trade mark for Esposito Jewelry Company. They started in the 1950's.

 

[Frankyg]

Or maybe ESP is Electro Silver Plate? Just a guess.

 

[KY PI]

It makes it so much better because it is "family related"! Congrats!