If you're looking at the cal aqua brand, CA uses borosilicate glass in thier products instead of the cheapo glass the chinese ebay replicas use. Borosilicate glass is significantly stronger and less likely to break; It is the same glass used in laboratory grade equipment. The cheaper glass products available in the hobby are very prone to breakage. Other quality glassware brands are ADA, Gush, Do!Aqua, and Borneo Wild.
Do yourself a favor and buy quality glassware from the companies that spend money on R&D, not cheap replicas.