E-Z cap bottles are designed to withstand pressure up to 125 psi for the cap and up to 145 psi for the bottle. This means that the bottle and the cap have been tested to withstand pressure up to these levels without failing or leaking. It is important to note that these pressure ratings apply to the bottle and cap when they are used properly and in accordance with the manufacturer's instructions. Using the bottle or cap in a manner that exceeds these pressure ratings can lead to failure or leakage, which can be dangerous. It is always important to follow the manufacturer's instructions and guidelines to ensure safe and proper use of any product.