Eddie Silva, a staff sergeant select with the U.S. Marines, left, learns to use a trekker GPS device with John Kingston, right, an orientation and mobility specialist at the VA Western Blind
Silva | Compass Ranger SL
Silva Multi Navigator GPS with Printed User Manual and Silva Case (ACO 013 362) | eBay
NAVIGATION SKILLS FOR WALKERS - Map Reading, Compass and GPS (Pathfinder Guides): Terry Marsh: 9780319091753: Amazon.com: Books