About guys who mention that sigma cialis doesnt work good. In my past experience every cialis,sildenafil etc from china dont work. I have 10g of useless cialis from another source. I managed to find out year ago why it doesn't work. Supposedly,something which is important in producing it is banned in china. So somehow they make sildenafil,tadalafil,some different way but it never works good. Now I dont know more about it,maybe sigma can clarify,all I know,only cialis that ever worked was pharmacy one or if you got raw from India