3524 Micro-porous Teflon® X射线荧光 XRF Film (Roll) 
0.2 micron pores. Installed on top of open ended cells. Gas slowly passes through the porous film during vacuum path operation. Supplied as continuous roll 2in. (51 mm) wide, 17 ft. (5 m) long in box. Allows pressure equalization inside cell without releasing liquid samples.