CATALYTIC CONVERTER SHIELDS EXPLAINED
What is a cat shield? Long story short, it's a metal plate / shield that covers the bottom of your car specifically over the catalytic converter. Why would you want do this this? Well unfortunately catalytic converter theft is a very common crime, especially targeted towards hybrid vehicles. First lets go over why thieves want them, how they steal them, and most importantly what you can do to help prevent becoming a victim of 'cat burglars'.

My 2022 Prius with a Miller Cat Shield
Why do thieves want to steal catalytic converters?
Catalytic Converters contain rare earth minerals such as platinum (Pt), along with palladium (Pd), and rhodium (Rh). All three of these platinum group metals, or PGMs, are extremely rare but have a broad range of applications in addition to catalytic converters. These are important for emissions on a car because they convert harmful compounds from your exhaust like Carbon monoxide into Carbon Dioxide, and Nitric Acid into Nitrogen and Oxygen. Because of the rare minerals, thief's will steal them and turn around to sell them to scrap metal dealers from anywhere between $50 and $250, with some going for $800 to $1,500 if they come from hybrid vehicles. Hybrid vehicles are usually a bigger target the normal cars because the quality of convertors used is usually better, and since the car is using electric power half the time, there is much less wear on the convertor meaning there will be more of the precious metals left to harvest. It also helps that most people drive hybrid vehicles conservatively and not like sports cars, leading to less abuse/wear.
How thieves steal catalytic converters
Unfortunately stealing a catalytic convertor is a lot easier than most people realize. Most thieves will usually work as a two-man operation. One person jacks up the side of the car, and the other slides under the car with a battery powered sawzall and cuts the ends of the exhaust pipe right before and after the cat. This can take as little as 30 seconds. You can search google or youtube for catalytic converter theft and see tons of security camera videos showing people doing this in broad daylight.
How to prevent catalytic converter theft
While there is no 100% fool-proof method to prevent theft outside of having the car inside a locked garage, a very popular and affordable option is installing a "Cat Shield". There are many companies that make them, but they are all basically a flat sheet of metal, either made of aluminum or stainless steel. Where normally the exhaust would be sitting under the car open to the elements, it then gets covered up with a huge plate that blocks all access for a thief to get any tools into position to easily chop it off. Some companies even offer custom bolts that are not your common type, so unless you have that specific driver, it will be a huge paint to get off. The idea is that it would turn a 30 second job into a much longer and louder process, so the thieves hopefully move onto another easier target and leave your car once they see yours has a shield. I would recommend Miller Cat Shields, I currently run their shield and think the quality and engineering is great. Check them out here: https://catshield.com/