The X/XN and R/RN Landing Nipples are utilized in the completion string to allow for the positive location of numerous subsurface flow control devices such as blanking plugs, bottom hole chokes, downhole recorders, etc. The X/XN and R/RN locking profiles allow for full selectivity in running flow control devices in completion strings where numerous profile nipples may be required. The X and R profiles do not have a No-Go ring machined in the bottom of the nipple where as the XN and RN do. Typically the No-Go nipple is the bottom profile in the string. Generally the R/RN profile nipples are used in higher pressure applications or those where smaller nipple sizes are required.