Texscan model CD-51 RF Xtal detector. 5 - 4000mhz, negative polarity. Female BNC coax connectors on each end. 2-1/2" L x 1/2"' diameter.Can be panel mounted. From an estate and have no idea what its usedfor but was told it came out of a microwave signal generator. Fd one oneBay asking $144. Price $25 postpaid.73Walt (N4GL)(352) 637-1755