If you have bought any one of the slim vape pen available in the market you can attest to their compactness and portability. However, one thing you might not have given too much thought to is the vape pen battery of the slim vape device in your possession. As slim as the CBD vape pen is, so also is its battery. The slim vape pen series are replaceable and can be bought in any vape shop or online. Here is a review of three of the best slim vape pen battery for sale currently available on the market.