This fused silica fitting insures stable, leak-free connections at temperatures up to 400°C, and undistorted ferrules that are easily removed and re-used. The union has a quartz liner to provide an inert connectoin zone of minimal volume and self-compensating nuts for correct sealing force even as temperature varies. It works with any type of capillary tubing. Special ferrules must be purchased separately (FS1.35-R10, FS1.45-R10 or FS1.75-R10, for 0.25mm, 0.32mm or 0.53mm ID tubing, respectively).