For a peg sensory portable this was a well made machine aimed more at stronger hobby players, than the toys market. The program was written by Dane, Kaare Danielsen who achieved remarkable results in just 4K. It is still thought to be the strongest 4K program in the world. Danielsen had already achieved a number of good results at tournaments with his program Logichess, including 3rd place at the European Microcomputer Chess Championship in London 1981. In the Explorer the program achieves an Elo rating of about 1400. The Explorer sold in good numbers for around £70 (219 DM) back in 1983 / 84. The Travel Sensor model is similar, but with a weaker program.