Do you receive small packages in the mail such as prescriptions or books? If so, you will want a secure locking mailbox that accepts packages.
The size of package that a locking mailbox accepts is limited by the size and design of the incoming mail area. The two most common incoming mail designs are the slot design or the bin design. The tradeoff is that mailboxes that accept larger packages can be vulnerable to fishing, as the same mechanism that allows for package delivery can (depending on the design) also allow for fishing hands.
If receiving the largest possible packages securely is important, then the Package Master or the Mail Manager is the best option. The Mail Boss Curbside is not designed for accepting packages, but can still accept a box of checks.
The Package Master features a large bin design that works in consortium with the patented Mail Shield, a backer door on a lever arm that prevents fishing. When the bin is fully opened, an incoming mail slot is revealed for depositing mail that is 1.25″ H x 10.5″ L. Parcels can be deposited in the bin, which accepts packages up to 3.5″-4.5″ W x 3.5″-4.5″ H x 10.5″ L.
The Mail Manager has a simple bin design which accepts small packages, too. The Mail Manager accommodates packages and mail in the same bin, and accepts packages up to 3.5″ H x 3.5″ W x 10.2″ L.
The Mail Boss Curbside features a slot design so the size of packages accepted is limited by the height and width of the slot. The incoming mail slot is 1.9″ H x 10.25″ W, which is just tall enough to accept a box of checks.
If you receive small packages and parcels in the mail frequently, you may want to consider either the Mail Manager or the Package Master. Remember, however, only USPS will be able to deliver packages to your mailbox. FedEx, UPS, and other shipping carriers are not (yet) allowed to deliver packages to your locking mailbox.