The Smart Sock 2 features entirely new hardware and design, based on feedback we heard from parents all over the world. With these changes, the Sock now fits babies both bigger and smaller—from 5 lbs. to 30 lbs. It also monitors babies through gentle motion, so you get live readings more often. And the redesigned Base Station offers wireless, drop-and-go charging—a huge time saver! Get an 8 hour charge in under 20 minutes, and a full 16 hours in 90 minutes. Paid over $300 for it only asking for $180