I was hoping that Ken Good could once again help me with this light. I will try to explain the problem I am having clearly. Basicly this is one of the new HA models and it is not working reliably 100% of the time. I intially thought the problems were in the tail cap and received another tail cap and I am still having the same problems. If the tail cap isn't very tight to the body there are times I will have complete light failure untill I loosen and then retighten the cap again. Please don't reply with the warnings about installing the batteries this is not the problem. Ken I am very thankfull for your help by getting me a new tail cap but unfortunatly this didn't resolve the problem. Did I just get a bad light that has very random outages? At this point I need this light so sending it into Blackhawk really isn't an option for me, and the company that sold it to me said he would refund my money he just doesn't have any more Gladius in stock. I am in a hard spot. I just don't feel comfortable carrying a Gladius on duty that isn't 100% 100% of the time.