Air filters come in various shapes and sizes. The most common types are disposable fiberglass filters, pleated filters, HEPA filters, electrostatic filters, and activated carbon filters. Each one has its own advantages and disadvantages, so it's important to choose the right one for your home.

Disposable Fiberglass Filters: These are the simplest type of air filter available and usually cost less than other options. They are made from woven fiberglass material that can capture particles as small as 3 microns in size. However, they don't last very long, so they need to be replaced every 30 days.

Pleated Filters: Pleated filters are more efficient than fiberglass ones since they can trap particles as small as 1 micron in size. They also last longer - up to 90 days before needing replacement.

HEPA Filters: HEPA filters are the most efficient type of air filter, as they can capture particles as small as 0.3 microns in size. They are also the most expensive option and need to be replaced every 6-12 months.

Electrostatic Filters: Electrostatic filters use an electric charge to capture particles, making them more effective than pleated filters. They usually last up to 6 months before needing replacement.

Activated Carbon Filters: Activated carbon filters are designed to remove odors and gases from the air, making them ideal for homes with pets or smokers. They usually last up to 3 months before needing replacement.

In general, it's best to replace your air filter every 1-3 months depending on the type of filter you have and the size of your home. If you have pets or smokers in your home, you may need to replace your filter more often. It's also important to check your filter regularly to make sure it's not clogged with dust and debris.