  We performed an analysis on the detection of a long lived stau at a linear
collider with $\sqrt{s}=500$ GeV. In GMSB models a long lived NLSP is predicted
for large value of the supersymmetry breaking scale F. Furthermore in a large
portion of the parameter space this particle is a stau. Such heavy charged
particles will leave a track in the tracking volume and hit the muon detector.
  In order to disentangle this signal from the muon background we explore
kinematics and particle identification tools: time of flight device, dE/dX and
Cerenkov devices.
