Sales of female condoms have been low in developed countries, though developing countries are increasingly using them to complement already existing family planning and HIV/AIDS programming. Probable causes for poor sales are that inserting the female condom is a skill that has to be learned and that female condoms can be significantly more expensive than male condoms (upwards of 2 or 3 times the cost). Also, reported "rustling" sounds from the original version of the female condom during intercourse turn off some potential users, as does the visibility of the outer ring which remains outside the vagina. Regulatory issues have also limited interest in manufacturing female condoms. In the United States, the FDA historically categorized female condoms as Class III medical devices, a category with more stringent requirements than Class II, which includes external condoms. Following proposals to reclassify female condoms, the FDA announced in 2018 that single-use female condoms would now be known as single-use internal condoms, and moved to Class II.