Recyclers
Recyclers are newer technology water pipes and oil rigs that are designed to constantly keep water moving within the chambers of your pipe (usually multiple chambers in these pipes). The constant flow of water creates a whirlpool-like effect that provides an incredibly smooth smoking experience.
Recyclers have very recently and very quickly become popular within the concentrate scene specifically, as the condensed chambers help to minimize the chances of vapor becoming stale and produces a drag-free smoke.