Class I devices represent the lowest risk; for example, dental floss and adhesive bandages fall under this category. Other examples include enema kits, elastic bandages, manual stethoscopes, and bedpans. Class II devices with higher risk and, according to FDA guidelines, “require greater regulatory controls to provide reasonable assurance of the device’s safety and effectiveness.” Blood pressure kits, powered wheelchairs, and some pregnancy test kits, for example, comprise Class II devices. Class III devices represent the higher risk category and include items such as knee prostheses and replacement heart valves (devices under this category usually require FDA approval before they are allowed to be marketed). Finally, implantable devices are items such as pacemakers or breast implants.