This is a screw-on, 90-degree valve stem extension.  It fits onto your existing valve stem and allows you to fill the tire from the side.  It’s useful when you have limited clearance between the end of your valve stem and the hub.  It makes tire inflation easier because you won’t be fighting with the spokes.

You’ll need at least 1.25″ clearance between the end of your existing valve stem and the hub for this extension to fit. The extension is 2″ long, and it has a valve cap that also serves as a valve core tool (tighten or loosen the core).

To install:
1.  Remove the valve cap from your existing tire stem
2.  Thread on the 90-degree extension (working quickly to prevent air loss)
3. Orient the extension so it points the direction you need
4.  Tighten the locking fitting on the base of the extension and check that there’s no air leakage
5.  Attach a CyclePump or other air source to the end of the stem
6.  Inflate tire to desired pressure
7.  Thread on the valve cap 
As part of your daily pre-ride check-list, inspect both tires for proper inflation and make sure the valve stem extension(s) is screwed tightly onto the valve stem.

*Note: NOT FOR USE WITH RUBBER VALVE STEMS except as a temporary aid for inflation.  Rubber stems will be affected by the weight of these extensions as the tire spins, and the rubber stem will bend and possibly fail, causing a rapid loss of tire pressure.  If you have rubber stems, these extensions should only be used for inflation, then they must be removed before riding.