AROMATASE INHIBITOR- Control unwanted bloat and estrogenic side-effects while on and off cycle with Shield. Shield is a suicide aromatase inhibitor that will knock out estrogen issues on short notice. Leave behind any worries of developing gynecomastia or high estradiol (E2) levels. This is a must have while on one of our pro hormone supplements. While not everyone will experience estrogen related side-effects while on or off cycle it is always best to lay on the side of caution.