Thread-safe Singleton (Best Practice)?

public sealed class Singleton
{
private static readonly object lockObj = new object();
private static Singleton instance;
private Singleton() { }
public static Singleton Instance
{

get

{
if (instance == null)
{

lock (lockObj)

{
if (instance == null)
instance = new Singleton();
}
}
return instance;
}
}
}