Precision-made platinum final apertures for Topcon(R)/ISI(R) scopes are available in the three most popular sizes. The ETEC(R) apertures have been designed especially for the needs of ETEC scopes. The 200 micron aperture is counter bored, making it useful as either a spray or final aperture. The 150 micron size is for use only as a final aperture. Platinum apertures may be flame cleaned. Sold in packs of 5.