POWET METER: How do I choose a power meter spider that is suitable for my bicycle?

Firstly, select according to the crank interface:

For example, if you are using XXE cranks, just select the spider with EASTON interface.

Secondly, select according to the chainring specification (number of spider’s holes and chainring BCD size):

If the original chainring is 110BCD 4-holes, you need to select the power meter spider with 4-holes (4S) 110BCD specification.