Truglo makes a nice one - with slider.





Fuse also makes a pendulum that's pretty nice (it's what I have on my bow). The pendulum swing is an option that you have to order from a Fuse Dealer.






The Fuse pendulum is lockable, and has a built-in level. I really like mine. I researched the heck out of this, and these two look like the two best options. The Truglo has a brighter pin, but I don't think it locks into place. The fuse is more expensive, but has a level and locks. I picked mine off ebay for $50.