"These things are absolutely fantastic!!!!! I put the lithium batteries in there and it's awesome. I told a few SAR people about them. Extremely well constructed also. I have people ask me about them when they are on the dog, cause I am out everynight with it." Fred Hassen "SIT MEANS SIT" Internet talkshow host http://www.lovemypets.com/sitmeanssit Dog Training for the Real World Las Vegas , Nevada