COBRA 250 is a prescription medicine used to treat erectile dysfunction (impotence) in men. It is a heavy dose which works by increasing blood flow to the penis .  this tablets are a prescription medication used to treat erectile dysfunction in men. The active ingredient in BLACK COBRA 250MG mg tablets is sildenafil citrate, which helps to increase blood flow to the penis to achieve and maintain an erection and delay your ejaculation timing for more then half an hour .