Bases Loaded 4 is the fourth installment for the Bases Loaded Series for the NES. It was released in November 1991 in Japan and April 1993 in the USA.
The game is the fourth installment of the Bases Loaded series, and the last of the original NES series. The series spanned three generations of consoles and eight total installments.
Source: Wikipedia, "Bases Loaded 4", available under the CC-BY-SA License.