When you want to throw some money at the thing,
a disc chainguard on the outside looks nice..
and either a second one on the inside of the single CR, or a chain-minder ,
to stop the unshipping on the inside..

I have a big one for my small wheel IGH setup which has a chain-tesioner,

Small ones are made for a Cyclo-cross bike option, 44,42t..

Paul's is a California manufacturer, rather than an exported idea ,
re imported from Asia. that is why his stuff costs more .