As an Amazon Associate, we earn from qualifying purchases. OS Engines Cylinder Piston Assembly: 21XR-B | Horizon Hobby OS Engines . OSMG4843 Gallery Attributes Brand name, Manufacturer name, ManufacturerOS Engines Extra Product NameOS Engines Cylinder Piston Assembly: 21XR-B | Horizon Hobby moq, multiple, tierMinQty11 MPNOSMG4843 qtyInStock0 SKU22203000 tierPrice1113.99 Distributor offers SellerSKUMOQIn stockMultiplePrices horizonhobby.com22203000111 @ $113.99