reo(a) The tubings are designed and manufactured in term of API Specification. 1.Size:1.9, 2 3/8", 2 7/8", 3 1/2" 4 1/2" 2.Connection : NUE, EUE , 8RD, 10RD, Round thread, 3.Steel grade: J55, N80, L80 and P110 Please feel free to contact us if you have any inquiry. The standard accessories we can supply are: 1.Pup Joints 2.Cross Overs 3.Couplings Accessories are available in the standard grades, with any of the connection types or combinations thereof, that are in our production program. Other proprietary connections and accessories, that are not part of our standard program, can be supplied on request.