Fitting Size Acceptable Outside Tubing Diameter 1/2".630" to .710"3/4".820" to .940"1"1.06" to 1.20" These Figure 8 Tubing End Closure fittings are used to close the end of low pressure poly tubing. Removability allows for easy opening for flushing or draining the lines. Very economical and easy to use. To Use: Insert poly tubing into one side of the figure '8' fitting. ; Fold tubing over and insert into the other side of the figure '8' fitting to close. ; Slide fitting down towards tubing fold to secure.;