All FIVE bombs that were found in the New York area used flip phones as a detonator: Fears grow of link between failed New Jersey attack and IED blast in Manhattan that injured 29
From the Daily Mail:
Three devices found in New Jersey and two in New York have used cell phones as detonators
The pipe bombs in New Jersey used flip phone timers and as did pressure-cooker device found in Chelsea
It's believed home-made bomb that exploded also used old-school flip phone as a detonator
Another similarity is lack of know-how that went into making the devices as three failed to detonate
Authorities aren't able to say if the New Jersey bombs are related to the explosion and device in New York
Currently, there the incidents don't appear related but de Blasio isn't 'taking any options off the table'