Yes, a gas-cylinder caddy can accommodate different cylinder sizes, but it depends on the design and features of the caddy. Some caddies are specifically designed to hold a particular size or type of cylinder, while others are adjustable or have features that allow them to accommodate various sizes. 
Adjustable caddies often have features like extendable arms, adjustable straps, or flexible bases that can be modified to securely hold different cylinder diameters and heights. These caddies are versatile and can be used in various settings, such as industrial, medical, or domestic environments, where different gas cylinder sizes are common.
Additionally, some caddies come with interchangeable components or modular designs, allowing users to customize the caddy to fit specific cylinder sizes. This adaptability is particularly useful in environments where multiple types of gases are used, each requiring different cylinder sizes.
When selecting a gas-cylinder caddy, it's important to consider the specific needs and the range of cylinder sizes you intend to use. Ensure that the caddy is constructed from durable materials to safely support the weight of the cylinders and is equipped with secure fastening mechanisms to prevent movement during transport. Safety features, such as locking wheels or brakes, can also enhance stability and prevent accidents.
In summary, while not all gas-cylinder caddies are designed to accommodate different cylinder sizes, many adjustable or modular options are available to meet diverse needs.