When purchasing a dive mask strap cover, it is important to consider the purpose of the cover. Some covers are designed to protect the strap from moisture and other environmental factors, while others may be used as a carrying case for the mask and its accompanying equipment. Additionally, some covers are adjustable in order to fit a variety of masks and straps.
To choose the right cover for your needs, take into account what type of environment you will be diving into and which type of mask you will be using. For instance, if you will be diving in salt water where corrosion is an issue, select a cover made from a corrosion-resistant material. If you plan on using a snorkel or scuba gear underwater, select a cover that can accommodate both items.
This decision becomes even more important when selecting a strap cover since different masks come with different size straps.