It is dual system with the clean water addition. Before use, please make sure that the three corners of the mop head refill are completely installed in the mop base and hear the "click" sound, otherwise it may come off.Perfect Fit for Triangle Spin MopEasily detach and snap on perfectly. thick fibers, work well as original.Multipurpose- These mop heads can make cleaning floors a breeze. It suits for wooden floors, ceramic tile, laminate floors, marble floors and other sealed hard floors. Also, you can use it for car or window cleaning.High Quality With Deep- Cleaning- Made of anti-abrasive microfibers, durable and machine washable.the microfiber mop head removes and absorbs tough dirt and grime easily.Making Mop Easier- These mop head has superior decontamination ability, both dry & wet use, the dry mops are used to absorb hair, dust, while wet mops are used to remove stains, meeting your various needs.