This filter is the INRAD filter #762, 9001.5 kHz, 600 Hz filter for an Orion. It is designed to be go in the Orion's 1000 Hz filter slot and improves the dynamic range by up to 13 dB. For more details, see http://www.inrad.net/product.php?productid=206&cat=92&page=1 $65.00 or best offer. tnx es 73 - John, W4AU