My wife and I both carry ASP's "Key Defender" on our keychain. It is very small yet seems to have enough "heat" (2 mil. SHU and 10%Capsicum) And it lists the exp. date on the refillable cartridge.<br><br> feel comfotbale with it. It is easily carried with little bulk. I have found it hard to find in stores but I believe it to be the best around.