Structurally stanozolol, also often referred to as winstrol(a product name of Zambon pharmaceuticals, containing stanozolol as the effective compound), is not capable of converting into estrogen. Likewise an antiestrogen is not necessary when using stanozolol , gynecomastia not being a concern even among sensitive individuals. Since estrogen is also the culprit with water retention, instead of bulk produces a lean, quality look to the physique with no fear of excess subcutaneous fluid retention.