That would be 500 grams twice? Am I correct in remembering that a cubic centimeter of water/saline weighs a gram? I think we have just solved the "where do you carry your last ditch PSK" question. Forget the necklaces, bracelets, and shoulder holster rigs: medical science is capable of providing us with PSK implants. I have seen ads for guys getting implants to improve muscle definition on their calves and thighs. The ETS forum crowd could opt for a sub-dermal DRPSK implant on one thigh, and a DR folder on the opposite forearm. The knife would need to be on the forearm so that the user could gnaw his way down to it for extraction. The personal locator beacon is another possibility...