1371 BELL JAR high straight form,Website: ,with knobProduct DescriptionMade from Heavy Glass. Complete with Glass Stopper. Perfect for isolating experiments from outside interference. This Bell jar is for use in only Physics Experiments to teach Science. It can withstand small amounts of Vacuum. How much Vacuum, we do not know. We are not liable for any use. For any use, we are not liable for any injury. Please use at your own risk. There can be Air Bubbles present in the body of the Bell Jar, when you buy this product you agree to buy if there are are any air bubbles. This will not be a reason for return or exchange. Any imperfections found in the bottom of the Bell Jar are air bubbles that occur during the firing of the bell. Every Bell Jar has this to some degree. It is not a damage or a crack. These imperfections will not affect the performance or integrity of these Bell Jars. To give additional strength to the bottom edge of the Bell Jar, so as to make it chip and break resistant an additional piece of glass ring has been glued / fused to the bottom. Because of the glue / fusing process, sometimes air bubbles develope giving them an appearance of cracks in the glass. This is not a defect and will not affect the working of the bell jar in the sound experiments. If you receive a Bell Jar and find these air bubbles there is nothing to worry about. These air bubbles or glue lines can be half an inch long or longer.There are 6 sizes available : 120 mm BELL JAR, 150 mm BELL JAR, 180 mm BELL JAR, 200 mm BELL JAR.,250 mm BELL JAR.Product informationSpecifications:Cat. No.I.D.　　mmInsideheight　mmQuantityPer　case1371120180121371150200613711502506137118025061371200300413712504002Product Features : Classic old school glass bell jar: heavy wall, machined base with solid knob top Machined base for air-tight seal to vacuum plates Makes an excellent display cover for small, delicate or high value collectiblesAlso used for making mini-terrariumsMaterial: GlassColor:clear