Seedlings grown from Opal apples (Malus spp.). 1 year old, 1 to 2 feet tall, bare root. These aren't the variety Opal, they are the offspring of Opal.
Opal is a flavorful yellow apple that is non-browning, itself a seedling of Golden Delicious x Topaz. Adam's Apples says "Opal is a gem. Her harmonious flavors and crisp texture are easy to appreciate and at the same time reward the attentive taster with a few subtle touches."
Photo: Optifruit, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons