Description Packaging 500 mg in Sure-Pac™ Standard 500 mg quantity is packaged in a Sure/Pac cylinder with stainless steel 1/4" male NPT valve. Nominal gas pressure at 21ºC is 7 psig for 500 mg. This pressure is slightly above atmospheric pressure. Care must be taken when extracting this product from the cylinder. This product may be available from bulk stock and can be packaged on demand. For information on pricing, availability and packaging, please contact Stable Isotopes Customer Service. Recommended products Stainless steel hose adapter Z146838 or stainless steel body mini gas regulator Z513547 is recommended.