The PG-A1 is very compact—measuring only 5.6 inches square—and engineered to accompany Topcon's modular GPS+ receivers such as the Legacy-E, Legacy-H and Odyssey-RS. Its rugged housing and metal groundplate protect the internal core components and can take a real pounding on the job site, such as hard surface pole drops.
The new PG-A1 delivers the highest GPS and electronic quality that you expect from all Topcon products.
Source: Topcon, Sept. 25, 2003