<unk>  are available in diameters of 50 mm to 105mm (about 2–4 inches). They are available in two different materials: latex and silicone.<unk>  are also available with different types of springs in the rim. An arcing spring folds into an arc shape when the sides are compressed. This is the strongest type of rim available in a<unk>  and may be used by women with any level of vaginal tone. Unlike other spring types, arcing springs may be used by women with mild cystocele, rectocele, or retroversion. Arcing spring<unk>  may be easier to insert correctly than other spring types. A coil spring flattens into an oval shape when the sides are compressed. This rim is not as strong as the arcing spring, and may only be used by women with average or firm vaginal tone. If an arcing spring<unk> is uncomfortable for a woman or, during intercourse, her partner, a coil spring may prove more satisfactory. Unlike the arcing spring<unk> , coil springs may be inserted with a device called an introducer. A flat spring is much like a coil spring, but thinner. This type of rim may only be used by women with firm vaginal tone. Flat spring<unk>  may also be inserted with an introducer for women uncomfortable using their hands. Ortho used to manufacture a flat-spring<unk> called the Ortho White. Reflexions also manufactured a flat-spring<unk> up until 2014. There are a number of variations. The SILCS<unk> is made of silicone, has an arcing spring, and a finger cup is molded on one end for easy removal. The Duet disposable<unk> is made of dipped polyurethane, pre-filled with BufferGel (BufferGel is currently in clinical trials as a spermicide and microbicide). Both the SILCS and Duet<unk>  come in only one size. Fitting bladder, 2: pubic bone, 3: urethra, 4: vagina, 5: uterus, 6: fornix, 7: cervix, 8:<unk>  9: rectum<unk>  usually come in different sizes and require a fitting appointment with a health care professional to determine which size a woman should wear. Single size<unk>  that do not require fitting also exist. A correctly fitting<unk> will cover the cervix and rest snugly against the pubic bone. A<unk> that is too small might fit inside the vagina without covering the cervix, or might become dislodged from the cervix during intercourse or bowel movements. It is also more likely that a woman's partner will feel the anterior rim of a<unk> that is too small during intercourse. A<unk> that is too large will place pressure on the urethra, preventing the bladder from emptying completely and increasing the risk of urinary tract infection. A<unk> that is too large may also cause a sore to develop on the vaginal wall.<unk>  should be re-fitted after a weight change of 4.5 kg (10 lb) or more. The traditional clinical guideline is that a decrease in weight may cause a woman to need a larger size, although the strength of this relationship has been questioned.<unk>  should also be re-fitted after any pregnancy of 14 weeks or longer. Full-term vaginal delivery especially will tend to increase the size<unk> a woman needs, although the changes to the pelvic floor during pregnancy mean even women who experience second-trimester miscarriage, or deliver by C-section, should be refitted. Vaginal tenting, an increase in the length of the vagina, occurs during arousal. This means that during intercourse, the<unk> will not fit snugly against the pubic bone because it is carried higher up the vaginal canal by the movement of the cervix. If the<unk> is inserted after arousal has begun, extra care must be taken to ensure the device is covering the cervix. A woman might be fitted with a different size<unk> depending on where she is in her menstrual cycle. It is common for a woman to wear a larger<unk> during menstruation. It has been speculated that a woman may be fitted with a larger size<unk> when she is near ovulation. The correct size for a woman is the largest size that she can wear comfortably throughout her cycle. In the United States,<unk>  are available by prescription only. Many other countries do not require prescriptions.
Diaphragm 
Epigastrium
Thoracic diaphragm
Airtraq
Gumma 
Ainhum
Azasteroid
Hippus