MX240

The above is the Chassis.

In the back you have room for power supplies.

If your AC is 110V. This is called LOW

You can use.

2 Power

4 Power 2+2 for redundancy.

If your AC is 220V. This is called HIGH

You can use

1 Power

2 Power 1+1 for redundancy.

You can run

1 Routing Engine

3 Cards

or

2 Routing engines

2 Cards.

Parts with BASE/Premium3- have the old Chassis with older midplane connector.

Parts with BASE3/Premium3- have the NEW Chassis with the new midplane connector {used for SCBE2 and high throughput cards}.

Prem3 are built to stock parts.