Synovex S - 10 Implants Steer Implants For Increased Rate of Weight Gain and Improve Feed Efficiency. For additional improvement in rate of weight gain in steers fed in confinement for slaughter, reimplant at approximately 70 days. Each dosage consists of 8 pellets containing 200 mg progesterone and 20 mg estradiol benzoate per implantation. This product was manufactured by a non-sterilizing process. Synovex S Steer Implants contain two pure steroid hormones, progesterone and estradiol benzoate. This formulation provides a complementary amount of each hormone for maximal growth stimulation. Synovex S is recommended for use in steers weighing 400 lbs or more. When properly administered, Synovex S implants increase rate of weight gain and improve feed efficiency.