KBAJ (105.5 FM, "J105 The Thunder") is a classic rock radio station licensed to Deer River, Minnesota, and is owned by Scott Hennen and Steven Hallstrom, through licensee Rapids Radio LLC.

Originally owned by Red Rock Radio Corp., it was a KQDS-FM simulcast.

On January 1, 2017, KBAJ was sold by Red Rock Radio Corp. to Lamke Broadcasting and rebranded as "J105 The Thunder", still keeping the classic rock format.

In the winter of 2017, KBAJ became the broadcast home for championship Grand Rapids High School hockey.

This article about a radio station in Minnesota is a stub.