Yes, they certainly do! If you run a sling library, we offer a 20% discount*. This only applies to library stock, of course (not carriers intended for personal use), and is not restricted to UK libraries, either!
We also have a ‘queue jump’ system for sling libraries – there is no need to enter our slot draw, just let me know, and we can arrange a convenient month for your carrier to be made.
* Discount does not apply to any wrap provided by us, or any artwork.