These are an alternative to the orange neoprene gear rubbers from Zenith/Zenair. 

Made from 75 Shore A SBR rubber with hi-tensile fabric reinforcements (operating temp -30° to +70° C). 

The set is of 2 x 18mm thick and 2 x 10mm thick 89mmm x 50mm rectangular rubber pads.  The 18mm upper pad moves the main gear down about 8mm on first fitting compared to the original part (subject to bedding in).  This has been shown to be useful for increasing clearance between strut bolts and gear.  The lower pad of 10mm is +/- the same thickness as the original part.  

On our aircraft we 'notch' for the gear pick bolt centrally (25mm centre line) on the lower pad, whereas the top pad generally sits best when notched to the 'outboard' - placing more rubber 'under the plane'. 

Installation, use and regular monitoring of these pads should be undertaken only by those understanding that these are NOT original parts and are provided as an alternative, for installation and operation at your own risk.

Ensure retaining nuts/gear plate are tightened as per Zenith/Zenair instructions.