There are several power meters that will work on an Easton EC90 SL or Easton EA90 crankset:
Spider Power Meters
power2max NGeco Easton Road Power Meter
The power2max NGeco Easton Road Power Meter is a great power meter for road cranksets. It’s a superb power meter in that it’s accurate, extremely durable, measures the power from both legs, is reasonably priced and allows you to keep your current Easton crankset.
The power2max NGeco Easton Road Power Meter is compatible with the Easton EA90 aluminum or Easton EC90 SL carbon crankset.

power2max NGeco Easton Road Power Meter
Sigeyi AXO Easton Road Power Meter
The Sigeyi AXO Easton Road Power Meter is another great option for Easton EA90 or Easton EC90 SL cranksets. Like the power2max, it’s accurate, reliable and measures power from both legs. It’s also a bit more affordable than the power2max while not sacrificing any features or functionality.

Sigeyi AXO Easton Road Power Meter
Pros: Moderately priced, VERY reliable, don’t have to change crankset, measures both legs
Cons: None
Power Meter Pedals
Power meter pedals can be installed on any crankset. They are reliable, accurate, easy to install and can be moved between bikes. We carry every power meter pedal available including ones from Favero, Garmin, SRM/LOOK and Wahoo. This includes both single- and dual-sided versions as well as pedals for SPD-SL, LOOK Keo and Speedplay cleats.
Pros: Easy to install, works on any bike, can move from bike to bike, don’t have to change crankset
Cons: None