Albert Barnes Commentary 1 Samuel 7:12

"Then Samuel took a stone, and set it between Mizpah and Shen, and called the name of it Eben-ezer, saying, Hitherto hath Jehovah helped us." — 1 Samuel 7:12 (ASV)

Shen was a tooth-pointed or sharp-pointed rock (See 1 Samuel 14:4), which is mentioned nowhere else and has not been identified.