I never knew these needed to be replaced on a regular schedule. The roofer said every 5 to 10 years. Mine leaked. I am looking at a few weeks worth of work and a lot of money to fix the rotted wood. My roof is 20 years old, the roof vents might have been leaking for 10 years or more! I found some "lifetime" guaranteed boots, $80.00 each, not cheep, but I bought them. These are not one size fits all. Each size fits only 1 size pipe.
Well worth it in my book.
Look online for them. The big box home stores only sell the "cheep ones" at $5 to $10 each. Extremely expensive when you need to pay a roofer a few hundred bucks every 5 or 10 years to replace them.
Just my .02 YMMV.
Randy Remove 333 to reply. Randy