Variable-rate master limited partnerships such as CVR Refining (CVRR) and Northern Tier Energy (NYSE: NTI) have been magnets for investor attention this year. These two refining MLPs posted high yields earlier this year but have since come back to Earth. PetroLogistics (NYSE: PDH), on the other hand, is one variable-rate MLP that's still sporting a high yield, and coming off a recent 55% quarter-over-quarter distribution increase. In this video, Fool.com contributor talks to Tyler Crowe about what PetroLogistics does, and why investors looking for yield should keep it in mind.