Promos plugin has ability to get products by features.
This condition has option "search among product features". By default searching is proceed among skus features.
Sku features
Let's assume that we need to search among the features of the sku, then the condition will look like this:
This means that the search will only be performed by the values of the sku features (Basics - sku settings):
Product features
Let's assume that we need to search among the features of the product, then the condition will look like this:
This means that the search will only be performed by the values of the product features (Features tab):
Consider specificity of this condition to get desired products.