This is a device used for contraception and for treating heavy periods but it can also be used to provide the progesterone component of HRT.
The Mirena is an intrauterine system, sometimes referred to as a coil, that releases a low and steady dose of a synthetic progesterone called levonorgestrel. It is a small, plastic T shaped device (around the size of a small matchstick) that is inserted into the womb and it lasts for 5 years.
A Mirena coil has the added benefit of providing contraception (if needed), and if you’re troubled by your periods, they usually become a lot lighter or disappear altogether when fitted with a Mirena