Our CLP helium calibrated Leaks are high-precision standards for calibrating leak detectors and ultra-high vacuum systems, and for serving as transfer standards for calibrating other helium leaks. They feature all-welded stainless steel construction, a premium all-metal shut-off valve, a glass-permeation leak element, and are bakeable for UHV applications. The CLP Leaks are part of a family of Helium Calibrators including the GPP, GPPT, and GPC Models offered by VTI that cover leak rates from E-12 up to E-3 atm-cc/sec and larger, as detailed in other brochures. The CLP Model is available with leak rates of E-6 to E-12 and is the only model made for the very low rates of E-10 to E-12 atm-cc/sec.