Spaceman Pop Top Jar - Various Sizes (X-Small) Go to amazon.com Related posts Check expert advices for 420 science? FeatureJars are made with super-thick borosilicate glassfeature heavy, pressed glass"pop-top" lids with strong gasket sealsMade in the USA. DescriptionJars are made with super-thick borosilicate glass; feature heavy, pressed glass, "pop-top" lids with strong gasket seals. Made in the USA.