Smaller-scale cremation urns, made to hold a portion of ashes rather than the whole set. These sit on a shelf, a mantel or in a memory box. They are not worn, and nothing here goes on a chain; for that, see memorial jewelry.
A keepsake holds a share. Think a few cubic inches against the 180 or so a full adult urn needs at one cubic inch per pound of body weight. Families usually buy two or three and fill them from the main urn using the small funnel supplied, or ask the funeral home to divide the ashes at collection instead. Some are used for a lock of hair or a little soil from a grave. Check the opening; most thread from the base.