Select options FL SERIES TILT 3/8″(10mm) DIAMETER BALANCE $6.78 – $10.90Product Code: FL SERIESProduct Description:The tube measures 3/8″ in diameter and houses an internal spiral rod with double pins to catch the pivot shoe. Spiral window balances come fully lubricated and ready to be charged.In order to find what size you have please measure the length of the tube only. This will give you the first two numbers you will need. the second two numbers is bast off of the color that it is Red = 20 and Green = 40. For example if the tube length is 21′ and the color is Red it is a 2120.