This is Siege Voyager Megatron. As is usual for his Cybertron mode, he transforms into an H-tank. He comes in a window box with pretty great artwork, instructions and two weapons. The weapons are integral to the tank mode.
This version of an H-tank is not bad. It is solid, and the turret can traverse. The main gun is huge and intimidating. While I have seen Cybertronian tank modes for Megatron in the comics that I prefer, this is one of the better versions that has made it to a physical toy.
The tank’s main gun is made up of two separate weapons: Megatron’s conventional cannon and a large rifle/sword. With the sword part removed and the turret turned backwards, it makes a passible mortar tank.
Megatron’s robot mode is good. It looks like Megatron. It has a few parts that retain the look of a pistol mode (hammer on the shoulders and the chest area). He is solid. Megatron is a more weighty toy than Optimus Prime, which is as it should be. The weathering on him looks more like mud splatters than battle damage, and I don’t really like his shade of grey. It would have been better if it was a bit more silvery. The few red parts pay homage to the original toy and break up the overall grey/black scheme a bit.
Unlike the recent Leader Megatron, his arm cannon can be properly positioned. It is removable. The other part of the tank gun can be used as a sword or gun (with pointy blade things). To fit with the Siege gimmick, there are plenty of peg ports and the weapons may be stored on the back. 
The biggest problem with this toy is that the head is supported with only a loose hinge behind the neck. So it tends to sink into the chest a bit. It is fine on the shelf, but falls down during play. It looks like there may have been a small part to hold the head up, but it is not on mine. Maybe it was removed from the design for cost saving.
Overall, this is the best Voyager Megatron I have seen in a long time. I even posted a long rant (before I started using pictures) on how there were no good G1 style Megatron toys. So I am happy to have this mostly accurate G1 Megatron.
Robot mode: 9
Vehicle mode: 8
Posability: 8
Playability: 9
Durability: 8
Overall: 9
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