This unit is similar to the #4A but does not use the Rocky's tubing. The hub is 4" and will take the 4" o/d Aluminum Irrigation type tubing (not supplied by Rocky's). This fits inside the 4" Hubs. #4 Permanent (4" Hubs) ground clearance to underside of tube approximately 5.75". Shipping weight is 9.5lbs.   Strong Die Cast Aluminum Construction Baked Enamel Finish Enhances Any Pool Easy To Use, In Most Cases By One Person Light Weight Yet Extremely Strong Not Effected By Sunlight Or Freezing Cold Quality Hardware FULL 10-YEAR WARRANTY PROBLEM FREE #4 Residential Permanent Installation Instructions (2pg. 262k) You will need the Adobe Acrobat Reader to view this file. Click here to download. © 2001 Rocky's Roller Systems Inc.   All rights reserved.