Slime Smart Tubes seal punctures while you ride due to being filled with the precise volume of Slime Sealant, preventing flats for anything up to two years. Instantly seals up to 1/8" (3mm) punctures Provides flat tyre protection for up to 2 years Pre-filled with environmentally-friendly Slime tube sealant Designed for 27.5" tyres (also known as 650b) Suitable tyre width are 1.9" upto 2.