No, really:
http://lmgtfy.com/?q=Nike+Flywire+jersey+collar
First news link, TBO.com about the Bucs has a good overview:
Most of the uniform changes relate to the construction and materials used, rather than individual team designs. Included is a "Flywire" collar used in the Nike Pro Combat line by several college football teams.
"Designed and engineered from the inside out, the new uniform focuses on creating a system where the baselayer, padding, jersey and pant work in concert," Nike claims in press releases announcing the new Elite 51 line.
Not all NFL franchises embraced the new technology. Nine teams chose not to adopt the Flywire collar, which Nike claims provides a "lockdown" seal with shoulder pads, and five teams decided not to use the "uniform system" at all.