To shorten your tube:

1. Remove the bite valve (you may need to soak the end of the tube with the bite valve in warm water for 5-10 minutes to make it easier to remove)
2. Trim the end of your tube to your desired length
3. Reinsert the bite valve (you may need to soak in warm water again)

To extend your tube:

1. Remove the bite valve  (you may need to soak the end of the tube with the bite valve in warm water for 5-10 minutes to make it easier to remove)
2. Attach to ends of the tubes together with our inline connector 
3. Trim to the preferred length and reinsert the bite valve (you may need to soak in warm water again)