Stan's sealant lasts anywhere from two to seven months, depending on local conditions. If you've been riding tubeless for a few months and haven't checked your tires, it's always a good idea to drop in some fresh sealant to make sure you aren't running low. Stan's revolutionary tire sealant is the most popular brand on the market, and comes in a handy 2-ounce refill bottle with a Yorker spout that makes refills super easy.
Flat tires aren't very common with tubeless systems but when they happen they can catastrophic if your sealant is all dried up. Keep one of these with you when riding to avoid having to end a ride due to the rare small puncture a little thorn or stick can deliver.
I love this stuff. I used to go through many tubes a month. I went tubeless about 7 years ago and I've never had an issue since. This bottle is the prefect amount of sealant to use when putting on a new tire or getting started with a new season.
I use a big bottle of stans at the house, but keep one of these in the pack for trail repairs. Has kept me from having to install a tube in a messy tire more than once and gets me on my way quickly.
2oz is exactly how much I add to my 29" Black Flag Pros. I may just be lucky, but I've always been able to seal a tire with just a floor pump and have had no problems with Stan's. Stan's does such a great job that I'll keep using it, and the no mess 2oz. container is so easy to put into the tire that if I did ever buy a pint, I'd probably just put 2oz into one of these bottles for the purposes of getting it into the tire easily.
Not much to say other than a small 2oz bottle of Stan's is usually the perfect amount to add when mounting a new tire. the small bottle and tip reduces the spills and mess that can happen with the bigger bottle/scoop.