Name the product that was registered in the sales order 'SO - 0005951'.
sales order 'SO - 0005951' refers to OrderNumber = 'SO - 0005951'; product refers to Product Name
SELECT T FROM ( SELECT DISTINCT CASE  WHEN T2.OrderNumber = 'SO - 0005951' THEN T1.`Product Name` ELSE NULL END AS T FROM Products T1 INNER JOIN `Sales Orders` T2 ON T2._ProductID = T1.ProductID ) WHERE T IS NOT NULL