When I go cycling, I carry my spare D/L which has a sticker on the back, not interfering with the magnetic strip, with wife's cell/ofc numbers, blood type, allergies, other pertinent info, then a piece of clear packing tape over the sticker to keep it more or less waterproof. Thankfully I've never needed to use it, but like all my other EDC, I'm prepared. Also have dogtags I were when going into the wilderness, mostly for body ID, not medical reference.