High quality, flint glass bell jars. Glass is crystal clear, allowing students to easily view experiments performed inside the jar. Bell jars with ground glass stopper offer the flexibility for evacuation or for pressurizing the inside of the jar using an external air source/pump. The nickel-plated vacuum plate (AP8618) works well with both the large and small bell jars or the polycarbonate plastic plate (AP1869) may be used with the large bell jars. Dimensions of small bell jars: 6" o.d. x 10" tall. Dimensions of large bell jars: 10" o.d. x 16" tall.