Prep Inlet Filter for 691/690-PO10, 692-PO01 and 692-PO05 Series and also Makeup-Flow Inlet Filter for all flow range

Straight Thru Hole, No Filter, 1 µL Volume, Pack of 5, goes with 690-0003 Inlet filter housing.

If you see more back pressure than you expected, then we may try this. 

In general, Straight thru option is for cases where absolute minimum dispersion is required, as the filter can add some amount of dispersion, and also for cases where another inlet filter is installed in line.