MTC Rapier Ballistic Rangefinder 1000m Bluetooth App Laser LCD 6x24

  
These are brilliant, you download the MTC Rapier Ballistic Rangefinder app and this when configured works out your exact hold over. There is several youtube videos about them. I dont have the earpiece it comes with but I use my apple airpods, any bluetooth earpiece connects, but what you will find is you use your phones to listen to the turret adjustment readings it gives you.