Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Invisible PFD does the job.

What's nice about the Sterns SOSpenders is that it fits any size person. Next is that it does not interfere with the limited space in a Kayak. I have not had the occasion to deploy it in a real emergency situation but I have practiced using the manual inflation tube and feel that I will be able to manually inflate the PFD and save the use of the CO2 cartridge in the event of a kayak sinking, which any folding kayak can do. And in the event of a capsize due to extraordinary rough water, can release the CO2 cartridge for quick deployment. I'm happy with the security that the SPSpender PFD provides.