Please recognize the importance of filtration for positive displacement pumping systems. Not all systems come with inlet filtration out of the box. Several models are configured for bulk tank feed and they must indeed be outfitted with filtration or the system may malfunction prematurely & will no longer be in compliance with the manufacturers warranty requirements.
In short, the systems with garden hose connections have a garden hose strainer, and the systems with float tanks have strainers in them for pre-feed to the pump. All other systems, with the exception of the SC30006D12 "Hammerhead" require an 80 Mesh (180 to 200 Micron) strainer. The SC30006D12 has a VF125 3/4" strainer built on board. For larger flow systems, the VF150 FILTER 1 1/2" T TYPE 180 MICRON is available (replacement screen VF153, replacement o-ring VF151)
Additional details are available in the Operation & Maintenance manual. https://www.hydrotek.us/_pdf/pressure-washer-operator-manual-2010.pdf