... five kinds of about: flat angle, 20*10 24*14 39*19 60*22 100*27 internal angel, 20*10 24 ... *14 39*19 60*22 100*27 external, 20*10 24*14 ... 39*19 60*22 100*27 flat tee, 20*10 24* ... 14 39*19 60*22 100*273 )Features: Good insulation characteristic:good ...