There are two types of IGC recording devices available, their use depending on the type of flight performance to be claimed:

IGC-Approved Flight Recorder (FR)
A device for recording the position and altitude of the glider using GNSS satellite data and barometric pressure for which an IDC-approval document has been issued by the GNSS FR Approval Committee (GFAC). There are three levels of approval listed in para 1.4.1 of Annex B to the Sporting Code for Gliding (SC3B):

For all flights (badges, diplomas and records).
For all badge and diploma Flights.
For badge flights up to diamonds only.
Position Recorder for Silver and Gold Badge Flights (PR)
A GPS recorder unit (not as secure as a IGC-approved flight recorder) which may be used for evidence for silver and gold flights only, under rules given in the Appendix to Chapter 4 of the Sporting Code for Gliding (SC3) and amplified in Annix C to this Code (SC3C).

The following pages give more details of these devices, with links to rules and approval documents.