post cap adaptor - need help
 

I just put on a new composite deck that has composite post sleeves (4 3/8") over 4" x 4" treated posts. I purchased 16 solar post caps but they are made to go right over the 4" x 4" wood posts (obviously 3.5" x 3.5" true dimension). So, I need an adaptor that will go over my composite post sleeve that my solar post caps can go on.

Anyone know a product I can purchase for this?

Thanks.