One of the bigger challenges of spreading LTE has been size; going 4G has tended to put on a little weight. A new Sierra Wireless embedded modem, the AirPrime EM7700, could be just the ticket to shedding those pounds. It's reputedly the thinnest module ever made, at a tenth of an inch deep, and should slot into an Ultrabook or tablet without anyone making snide comments about the extra bulk. The EM7700 is still using the Qualcomm MDM9200 Gobi chipset that we spotted in the related MC7700 (pictured here) and Lumia 900, and won't have world 4G roaming -- in fact, it's explicitly tuned just to AT&T's LTE frequencies, so there's no question as to who gets first crack. Shipments are due to start in the last few weeks of spring and will make it entirely probable that AT&T's next wave of 4G mobile gear will have slimmed down a few belt notches.