How to make an extension block with numeric drop-down parameters?

I want to create a makecode extension with a block that has a numeric drop-down. For example values of 4.096, 2.048, 1.024.
I recollect the drop-down values are made as enums, but I can’t see how to use numbers as enum values.
Any help appreciated!

I’ve got round the problem by using typescript //% formatting, like this:

num FSR {
//% block=“6.144V”
//% block=“4.096V”

Which does the job.