Size of a כגריס ועוד

Why does the rov hold that a כגריס ועוד is the size of a nickel? Does the rov have a Teshuvah on this matter? Can you please explain?

Sorry can’t help you on this one. Ask him. Just wondering though, it’s pretty close in size to shiurim mentioned by many Poskim. What makes you ask?

Thank you. Really was curious because I hadn’t come access this opinion.