Memorex MK1995 - Manual (Page 28)

Notes for Better Communication
25
1. Your MK1995 GMRS radio has been designed to maximize
performance and improve transmission range in the field. To
avoid interference, it is recommended that you do not use the
unit closer than 5 feet from another unit.
2. For better transmission results, keep your mouth about 2-3
inches from the microphone and speak slowly in a normal
voice.
3. Reverse polarity( + / - ) may cause serious damage to the unit.
Make sure not to reverse the polarity( + / - ) of the batteries in the
battery compartment.