Tim and Tim have donned their SAFER units that will be their backup if they ever lose grip of the International Space Station. The SAFER backpack (Simplified Aid For EVA Rescue) a jetpack that expells nitrogen jets to propel the astronauts back to safety. To keep weight and size down only a small amount of nitrogen propellant is stored, so the backpack is to be used in emergencies only.
During their spacewalk the astronauts will move around by hand using the handrails. When they swap the failed Sequential Shunt Unit Tim Kopra will install a foot restraint to have both arms free.