The Polar Plug is a rechargeable heater that attaches to the handlebar of a bicycle. When this product is installed, the grip temperature rises to 40 degrees and warms up, so there is no need to worry about freezing your hands even in the middle of winter.
This product is not drop-type within 17.5mm in diameter and can be inserted into most handles. Charging time is 2 to 5 hours. The heater can reach from 100 degrees to 105 degrees. Polar Plug also raised funds through Kickstarter, a crowdfunding site. Related information can be found here.