Foresters and land managers call these hip chains, string boxes or topofils. This is really good unit because it holds a 6500 meter spool of measuring thread - just tie off the tread, hit the zero reset and start walking - at the end of the measuring point check the dial window and read off the distance in meters. It is such a simple tool that really does the job and the string quickly degrades in the elements so no wildlife is affected. It is basically a light cotton thread that is just strong enough to hold together while you measure. I used this one when I worked in forestry. The small hip chains retail for about $120.00 and this top of the line unit is around $200.00 new but they are hard to get. Comes with a spool of thread ready to go. Replacement spools are available from many online forestry equipment retailers.

---