These are sticky patches that go on the skin a bit like a plaster. You apply them to your thigh or buttock (non-hairy places are best) and change it (usually) twice a week. The hormone is absorbed into the skin and enters the bloodstream, delivering a steady, continuous dose of oestrogen.
Patches can sometimes leave a sticky residue when removed, and some people have a skin reaction to the adhesive used in some of the patches. The patch is visible but clear and usually worn discreetly.