Haih sama lah, susah nak cari exact info pasal tu! Based on my experience, silicone bottles mcm Como Tomo & He or She tu usually boleh tahan around 1-2 years with regular use before the silicone starts degrading, especially kalau sering kena heat sterilization. Mine dah jadi mcm lengket-lengket and slightly discolored after tu je, tapi memang lama gila sebab tahan banget haha. Best way is tengok condition dia ja, kalau dah ada cracks, sticky texture, atau smell weird, time to replace, safety first for baby. Normally I replace when switching to sippy cups anyway, so tak rasa sakit sangat di pocket.