Advice about tuning pegs

I've posted a request on another thread about ubass tuning pegs. After a lot of research I've discovered that the Kala ubass uses a Hipshott tuner.

My question is, can someone tell me what the meanings of the measurements given for their tuners. One tuner measursi 3/8" and another is 1/2" - am I correct in assuming that this refers to the diameter of the peg itself taken below the top collar?

Thanks

Seems to be...go to hipshotproducts dot com...

Yup - thanks. Sent them an email but so far no response - sigh.