I tried trading a few of these, and like swipe said it is tough to get filled between the spread. If you are patient and the market goes your way, you will eventually be at the inside and get filled. This is usually at a point where the MM can arb a profit - if you could be the one to get this fill, you could arb a few pennies. So, ime you would probably have to be a MM to be able to arb these consistently right now. Basically, the MM's are making the market by being able to arb a few pennies when they fill you. Fills at the bid or offer are instant though, and your order between the spread will be displayed immediately.