Hexagon nipples

The image shows three technical engineering diagrams of pipe fittings. The left diagram labeled "Equal" shows a cross-section of a straight coupling with dimension line "K". The center diagram shows a hexagonal end view with dimension "I" across the flats. The right diagram labeled "Reducing" shows a cross-section of a reducer fitting with dimension line "L". All diagrams include internal thread details and dimension lines in red, with a center axis line in blue.
Two stainless steel pipe nipples with external threads on both ends. The nipple on the left is longer than the one on the right.
A table of pipe nipple dimensions and weights, including nominal bore, width across flats, length, and weight per piece for equal and reducing nipples.