Fluidmaster PRO1T12CS   Click-Seal Stainless Steel 12-Inch Toilet Supply Line Fluid master Twist Click Seal Braided Stainless Steel Toilet Supply Line. - Click seal connection No Burst, 3/8" female compression thread X 7/8" female ballcock thread Seal nut clicks when connector has the proper seal, preventing over tightening and cracking of the nut and fill valve shank