Safe: Understand how to manage the risks in your activity.
 

Each participant must understand the possible risks, both physically and psychologically. The sexual activity should cause no permanent emotional or physical harm (except, of course, where branding or piercing is involved). The safe toys (dildos, butt plugs) are clean (or have new condoms ready for switching partners), that slings are secure, that other people putting their fingers into the lube don’t contaminate it.

Knowledge of participants’ bodies – how they work, what they can and can’t do – is fundamental as is a basic knowledge of hygiene. That includes taking precautions so that STIs (such as HIV) are not spread.
 

Sane: Being rational, understanding decisions are made when in a healthy state of mind and limits that are not crossed on impulse.

Those who are out to prove that they are kinkier, more fun, or more loving than the rest can prove just as volatile through dopamine and endorphins and lust as those wasted on chemicals. Tops who ‘know how to dish it out’ and bottoms that ‘want to prove they can take it’ are more likely to stray beyond safe limits than those who know where the line between fantasy and reality begins and ends.
 

Consensual: Participants must agree to the activities and what happens to them.  Consent is outside the scene.

Consent means agreeing specifically to the activities, and you can withdraw that consent at any time. Explaining to your partner what you will be doing should excite them and will gain consent, rather than them being surprised and hurt when you cross the line. It’s important to be explicit.  BDSM and all the variations of it should be about mutual pleasure, however it is gained.  Not unwanted abuse.
 

Informed: Participants must be able to understand the risks and pleasures. 
 

Informed means knowing exactly what you are consenting to and that you can change your mind if you don’t like it. If you do not understand the meanings of a phrase, then you cannot truly consent to it.  ‘Trust me, you will enjoy this mysterious thing’ is not gaining informed consent.  It is requiring an open agreement to the wishes of the other person and exposes you to great risk.

SSC vs SSCI vs RACK
Of these models, we specifically endorse SSCI.