made from high borosilicate 3.3 glass tubing directly,uniform.High quality,reasonable prices,sales to UK,CANADA AND U.S.A etc., made from high boro 3.3 glass tubing directly.with heavy wall.uniform.high quality with reasonable prices.have a good sales market places in UK,CANADA AND U.S.A.PLEASE SEE THE FOLLOWING SIZES: Socket sizeCone size14/2314/2314/2014/2019/2619/2619/2219/2224/2924/2924/4024/ ...