Most trailer ball locks list compatibility with 1-7/8-inch, 2-inch, and 2-5/16-inch couplers. Some listings specifically note fit for 2-inch and 2-5/16-inch straight-tongue couplers.
Hitch balls commonly use a 1-inch shank diameter, with shank lengths shown around 2.0 to 2.13 inches in the product details.
Kits commonly include multiple keys—examples show 3 keys with some coupler locks and 2 keys with several receiver-style locks.
Some coupler locks offer multi-level adjustment; at least one model lists support for 11 different height settings to accommodate various trailer and vehicle combinations.
Kits often include a coupler lock or ball mount, a hitch ball or padlock, mounting/locking pins, and multiple keys. Some listings also mention bottom connectors or a user manual.