rotaryxperamental

Hey guys, I am thinking of buying that universal 134a conversion kit from the autho parts store, and I have a question. Does the kit come with all of the O-rings for the ac lines or do I need to buy them separately? If I have to buy the o-rings, can I get them at the parts store? I know I need to change the receiver/dryer, but is this all I need:
1)134a Conversion kit
2)O-ring kit?
3)Receiver/Dryer

Thanks guys!!!!!