I had previously installed a Laserlyte on my small frame Taurus .38 SPL revolver and was happy with it (MidwayUSA had a sale on these) based on that I bought on eBay a Laserlyte for the Kel-Tec PF 9....Unfortunately I found the batteries would drain very quickly even with little to no use (lasting about 3-4 weeks). That , of course renders this useless for self defense. I contacted the customer service at Laserlyte leaving a VM and an email; within 15 minutes of my VM I was contacted by Sonja in Customer service who also had read the email- who offered to ship me a replacement unit immediately (with a prepaid return envelope for the defective unit) so as to minimize any delay. I received the replacement a few days later and was floored that they included a pack of a dozen extra batteries (the unit takes 4 small watch sized batteries-the package comes with the batteries installed in the sight plus 4 extras). I am assuming this is enough for 2 or more years (the other Laserlyte on my Taurus which is several months old shows no signs of a weak battery). I chose the Laserlyte as it is very low profile; the PF9 does have a rail mount for acessories-but frankly for such a small gun adding a light or rail mount laser defeats the design of this! Anyway, just wanted to share my positive experience!!!!!