2a first mounting facility thread class right-hand first mounting facility 0.312" first mounting facility thread length 1.109" overall length 0.859" overall width 32 second mounting facility thread quantity per inch unc first mounting facility thread series
2a single mounting facility thread class 1.109" overall length 0.859" overall width 48 single mounting facility thread quantity per inch unc single mounting facility thread series
2b single mounting facility thread class 1.531" overall length 1.430" overall width 32 single mounting facility thread quantity per inch unc single mounting facility thread series