modified pucks were engineered to have the same weight and balance as an unmodified NHL puck; chief engineer Rick Cavallaro noted that players could tell if the puck was even slightly off its normal weight, as it behaved differently. While the puck passed rigorous tests by the NHL to qualify as an official puck, some players who tested the puck felt that it had more rebound. The puck emitted infrared pulses that were detected by cameras, whose shutters were synchronized to the pulses. Data from the cameras was transmitted to a production trailer nicknamed the "Puck Truck", which contained SGI workstations used to calculate the coordinates of candidate targets, and render appropriate graphics onto them. The puck was given a blue-colored glow. Passes were indicated with the bluish glow plus a tail indicating its path. When the puck moved faster than 70 miles per hour, a red tail was added. The blue glow was initially intended as a placeholder effect; while Fox Sports' graphics department intended to create a different design for the graphic, the blue blur was kept. Despite rumors that Fox employees would sometimes go into the stands to retrieve a puck that left the playing area, the pucks were not re-usable, and only had a battery life of around 18 minutes. Around 50 pucks were brought to each game where FoxTrax was deployed, while Cavallaro noted that they were prized by spectators. Public response The FoxTrax system was widely criticized by hockey fans, who felt that the graphics were distracting and meant to make the broadcasts cater towards casual viewers; sportswriter Greg Wyshynski stated that FoxTrax was "cheesy enough that it looked like hockey by way of a Mighty Morphin Power Rangers production budget", and considered it "a sad commentary on what outsiders thought of both hockey and American hockey fans". Acknowledging that Canadian-born journalist Peter Jennings (who was interviewed as a guest during the 1996 All-Star Game that introduced the technology) stated on-air that Canadians would "probably hate it", Wyshynski suggested that FoxTrax was an admission that American viewers were "too hockey-stupid to follow the play" or "need to be distracted by shiny new toys in order to watch the sport." In 2002, an informal poll by ESPN solicited opinions from readers on the worst innovations in sports history, without specifying choices in advance. The Fox glow puck came in 6th place, just behind free agency.