Nipple Clamps

What is the longest length of time you have worn a set of clamps for.

and are you male or female.

http://www.lovehoney.co.uk/product.cfm?p=24237 On their most pinchy setting

3 Hours or there abouts, Male

About 2hrs forr me

I'm a relative new comer to nipple clamps, but ouch ! I love them....but don't you have to be careful and limit the amount of time they are worn? Female, by the way.