(16 alpha(R))-16,17-((1-Phenylethylidene)bis(oxy))pregn-4-ene-3,20-dione. A progesterone that has been used in estrus synchronization and has been evaluated as an injectable contraceptive in combination with estradiol enanthate. It is also used therapeutically as a topical anti-inflammatory and is applied topically in the treatment of acne.