◆It is a special transmitter can be used with 5 watch receivers (APE6800 only), one button for one watch receiver. ◆Five-button Pager, can also work with other watch receiver and fixed receivers, same function as APE750/APE150. ◆There are five buttons: Ⅰ、Ⅱ、Ⅲ、Ⅳ、Ⅴ ◆Silica gel button, felt comfortable ◆Size:4.5*2.4*0.4 in (113mm*62mm*9mm) ◆Four CR2032 button batteries