You can also use this Measuring guide for the King JCobra & JCobra
HOW DO I KNOW WHAT JNAJA SIZE TO BUY?
With the help of Jelle from Velv’Or we’ve put together this simple guide to help you measure yourself to ensure you get the correct sized JNaja for your penis size. As you’ll be wearing the JNaja for long lengths of time you need to ensure you pick the correct ring size. You want something that gives a heavy amount of pressure when erect, but not too much so it cuts off the blood circulation. You also want a pleasurable amount of comfort when flaccid.
1. First you need to be fully erect.
2. Take a piece of string and slip it behind your balls and tug it up nice and tight around the base of your penis (close to your body).
3. Now mark the string on both sides where they come together (making sure that it feels comfortable).
4. Remove the string and measure the distance between the 2 marks you’ve just made (mm). This gives you your circumference.
5. Divide the circumference by 3.14 to calculate the size of JNaja you require