IP ratings are used to define the degree of protection of electrical enclosures against intrusion from foreign bodies such as dust, water, dirt and moisture.  These ratings are published by the International Electrotechnical Commission (IEC).  IP ratings consist of a two-digit code, with each digit representing the the degree of protection. When consumers purchase waterprooof wireless doorbell kits, they can refer to the IP rating on the product specification and purchase one based on their needs.

The first digit signifies the protection level against dust and foreign objects, such as tools and human fingers, ensuring that live components within the device are inaccessible to avoid electric shock.  The second digit indicates how well the device resists moisture and water penetration.  And the higher the number, the greater the protection!  

• First Digit(solid particle ingress)

Dust protection is categorized into six levels, numbered 0 to 6, with each level indicating the device's capability to protect against particles of diverse sizes.

- IP0X: No protection, no specific design to protect against the ingress of solid foreign objects.

- IP1X: Prevents entry of solid objects larger than 50mm in diameter such as the back of a hand, but no protection against deliberate contact with a body part.

- IP2X: Prevents entry of solid objects larger than 12.5mm in diameter, fingers or similar objects.

- IP3X: Prevents entry of solid objects larger than 2.5mm in diameter, tools, thick wires and other tiny items.

- IP4X: Prevents entry of solid objects larger than 1mm in diameter, most wires, screws, large insects, nails, etc.

- IP5X: Partial protection against dust that may harm equipment.

- IP6X: Completely dustproof.

• Second Digit(liquid ingress)

The waterproof rating is divided into 9 levels (but not all numbers have corresponding levels), representing the device's protection capabilities under different water flow conditions.

- IPX0: No protection.

- IPX1: Prevent vertically falling droplets, such as condensation.

- IPX2: Prevent dripping water from entering when it is tilted at 15 degrees.

- IPX3: Prevent water spraying within 60 degrees from the vertical direction of the equipment.

- IPX4: Prevent water splashing from any direction.

- IPX5: Prevent water projected by a nozzle(6.3 mm) from any direction.

- IPX6: Prevent powerful water jetting, even direct high-pressure jets(12.5 mm nozzle).

- IPX7: Full immersion up to 30 minutes at depths between 15 cm and 1 meter without damaging.

- IPX8: Completely immersed in water for a longer period of time and under a certain pressure without damage.

- IPX9: Resist high temperature and high pressure water spray, and withstand water shock in high temperature and high pressure environment.

Based on the provided information, the rating IP21 ensures protection against finger contact and dripping water, so wireless doorbell switches meeting this standard are suitable for indoor use.

Additionally, the lP44 rating indicates that the product is protected against solid particles over 1mm in size and can resist low-velocity water sprays from all directions. Wireless doorbell push button meeting IP44 standard can basically be installed at outdoor doorstep. So we recommend that consumers choose IP44 waterproof Kinetic wireless doorbell when purchasing doorbells for homes or studios. 

Advent Battery Free IP44 Weatherproof Kinetic Wireless Doorbell, Model FB: