2 linear rails " 18.25 long with 2 bearing blocks each Check out
http://www.us.nsk.com/public/enu/351_912.asp for more information on the bearings (NSK LS20 S) they are in very good shape no rust or other blemishes these are heavy duty rails are 20mm wide (".787) iam listing them as used because i do no know if they are new or used but they look new biding starts at $25 sh calulated
http://cgi.ebay.com/ws/eBayISAPI.dll...sPageName=STRK LOOK AT MY OTHER EBAY SALES THERE IS A 2ND SET SAME SIZE