Garmin/Foretrex series
The Garmin Foretrex is a series of wrist-mounted GPS devices. They do not support mapping, but can record a tracklog and waypoints.
Foretrex 101/201
Old models, now discontinued, similar specification to the eTrex Yellow or Geko 201.
Uses a serial connection (via Garmin adaptor; a serial to USB adaptor works), can upload/download tracks and waypoints e.g. with GPSBabel or GPS TrackMaker.
The 101 uses 2 AAA batteries, the 201 has a built-in rechargeable lithium-ion battery, otherwise they are identical.
Foretrex 301/401
Uses 2AAA batteries, has a high sensitivity reciever, and can record 10,000 points in the tracklog.
Work as USB Mass Storage devices. The tracklog and waypoints are saved in the file Garmin/GPX/current/Current.gpx
The 401 has an electronic compass and barometric altimeter, and can connect to a Garmin heart rate monitor or cadence sensor. As of firmware version 2.30, the heart rate / cadence data is recorded in the GPX track.
GPS only. No GLONASS or WAAS support.