A storage container may include a hollow main body, a lid, and an attachment mechanism for removably attaching a shackle holder. The hollow main body has a plurality of sidewalls, a first end, and a second end, opposite the first end. The lid may be disposed on the first end of the main body and the attachment mechanism may be disposed on the second end of the hollow main body. The shackle holder may be configured to retain a shackle. The shackle holder is capable of being disposed on storage containers with main bodies that vary in size.