Contraceptive implant.See table under 'Effectiveness': https://en.wikipedia.org/wiki/Comparison_of_birth_control_methodsTypical use failure rate during first year: contraceptive implant 0.05%vasectomy 0.15%IUD 0.8%pill 7%male condom 13%
How so? Isn't it just a rag stuffed into a bottle with gelled gasoline?