I bought these to bring some of my O model railcars up to recommended weight. Although this is not their main purpose, they are excellent for this application. Cars roll better and stay on track when the weight is adjusted to NMRA standards. In O scale 5 oz + 1 oz per 1 inch vehicle length. So a 10 inch (40 foot) car should weigh about 15 ounces. Thanks to the adhesive backing of these 1/2 weights, they can be e.g. B. easily attach to any hidden spot. under the body of a car or in the saloons of covered wagons. I check the car's weight with an inexpensive digital kitchen scale before adding these weights.