Which type(s) of circumcision is/are valid by the Islamic rules?

There are four main categories of male circumcision. i.e.: 1. Low and Loose 2. Low and Tight 3. High and Loose 4. High and Tight
- Which one(s) of these are valid as-per the Islamic rules? Meaning which one of these fulfill the requirement(s) that Islam mandates in order for the circumcision to be considered valid? Or else it's not. - Are there any mandatory requirement(s) for a Islamic circumcision? If so what are they? - What's ruling on the removal of the frenulum?