So they designed bitkey it in a way that allows you to spend Bitcoin without the bitkey itself in a secure way, straight from your phone (that’s what’s considered a “hot” wallet) under a set amount you specify. 

For any amounts larger than what you set, you need the bitkey to sign the transaction (that’s the “cold” wallet). 

But to enable all of this, bitkey is not your typical 12 seed phrase wallet. It’s a bit more complex under the hood.