My Cousin's Bat Collection

These bats, along with several others, were collected by my late cousin. His father is interested in knowing more about the bats, why his son would have been collecting them, etc. It appears that my cousin was buying about one a month for a couple of years. Most appear to be full-size useable bats, but for whatever reason, most do not have a length listed on the bottom of the knob. Can anyone help us?