There are three options in the link, which respectively include:
For 1 sensor without a transmitter,
For A kit including 1 transmitter and 1 sensor,
For 4 sensors without a transmitter.

Please purchase according to your needs.

The transmitter can be reused for up to 4 years, while the sensor needs to be replaced every 14 days. If you don’t have a transmitter, please purchase a complete set including 1 transmitter and 1 sensor for the first use.

Tips for After-sale:

1-We would be appreciate it if you could give us a five-star review if you are satisfied with our products and services.

2-Communication is always more helpful than dispute and negative feedback. Initiate a dispute help nothing but increase the misunderstanding.

3-We are committed to providing excellent customer service and resolving any issues you may have. If you are not completely satisfied with the product, please let us know and we will do our best to address your concerns.