There’s some law of nature that says you run out of smartphone battery just as you’re making the most important call or text of the day.

Now, a new keychain device —¬†billed as “the world’s smallest smartphone battery pack” to distinguish itself from the zillions of other battery packs¬†— wants to give you an extra boost to take along.

The PulsePak, a product of Utah-based product development firm Blade Electronics, is now seeking to raise $25,000 on crowdfunding site Kickstarter over the next 22 days to cover tooling costs and the first production run.

The 300mAh lithium polymer battery, measuring 1.5 x .9 x .5 inches, can handle in excess of 500 charge cycles, lasts up to four months on a single charge, is targeted for the moment at Android devices, and is $15 for the first 500 backers.

“Every other power pack that I’ve seen or owned,” says Blade Electronics co-founder K.C. Corbetter in a video on the crowdfunding page, “is way too big to actually carry around with you.”

A micro-USB connector on the “aircraft grade aluminum” body plugs into the phone. The company said that for medium-sized phones such as the Samsung Galaxy S4 and the HTC One, the PulsePak offers another 1.5 hours of additional talk time or equivalent for other tasks. Larger devices, like the Samsung Note 3, get an extra hour.

Enough to call the tow truck or make a temporary apology to your aggrieved boy/girlfriend.