SnapIt! Power Chair Adjustable Drink Holder Power Chair Drink Holder. Four position adjustable drink holder holds a wide variety of beverage containers from large 3-5/8" diameter sport bottles down to small water bottles and aluminum cans. Mounts under armrest with SnapIt! System mounting arm. Select your chair from the drop down menu. SnapIt! Tubing Diameter Size Chart Fractions Decimals Metric Flat Length 3/4" .75" 19mm 2.356" 7/8" .875" 22mm 2.75" 1" 1" 25mm 3.142" 1-1/8" 1.125" 29mm 3.53" 1-3/16" 1.1875" 30mm 3.73" 1-1/4" 1.25" 32mm 3.927" Step 1) Find a piece of paper measuring at least 4" x 1" Step 2) Now wrap the piece of paper around the section of tubing you would like to mount your SnapIt! cup holder. Step 3) While the paper is wrapped around the tube, mark the end of the piece of paper with a pencil. This will measure the entire circumference of the tube. Step 4) Now measure from the end of the paper to the mark with a ruler. Step 5) Look at the table above. Find the "Flat Lenght" and it's correlating "Diameter in Fractions", "Diameter in Decimals" and "Diameter in Metric" Now you will have the diameter of the tube!