Nexplanon, or the almost identical Implanon, is a single-rod subdermal contraceptive implant made by Merck & Co. that is inserted just under the skin of a woman's upper arm and contains etonorgestrel. Nexplanon/Implanon are a type of long-acting reversible contraception, the most effective form of birth control. Nexplanon is essentially identical to Implanon except Nexplanon has 15 mg of barium sulphate added to the core, so it is detectable by x-ray. Nexplanon also has a pre-loaded applicator for easier insertion. Implanon was first approved for use in Indonesia in 1998. Subdermal contraceptive implants are now used by 11 million women around the world and approved for use in over 60 countries as of 2003.