This is a black Altec Lansing M402 RC remote control for an alarm clock.
The M402 RC Altec Lansing replacement remote control has buttons that select the source, turn on and off the power, skip ahead, skip back, alarm, play, pause, p1, p2, p3, p4, and a snooze button.
It uses a CR2025 3 Volt button cell type battery. These are easily found at Walmart.