The insertion devices under construction for phase I of the Swiss Light Sou
rce (SLS) are described. Five undulators and one wiggler will be installed
in four straight sections of the third generation 2.4 GeV SLS storage ring,
under construction at the Paul Scherrer Institute. To provide undulator ra
diation in the energy range from 10 eV to 18 keV, both long period and shor
t period, small gap undulators will be installed. (C) 2001 Elsevier Science
B.V. All rights reserved.