Best extenders for steel shafts

I need to lengthen some new irons and I see that there are now wood extenders.  Any thoughts/insight on the best extender.  I typically use graphite ones.

When I purchased my irons in January, I was fitted for plus 1" on my CG16's at Golf Galaxy and I'm sure this is what was used http://www.golfgalaxy.com/GolfWorks-Steel-Shaft-Butt-Extensions/PAPMACBGMPOCEKCP/Product , pretty standard.Assuming you have steel shafts in your irons. Otherwise I've used these on graphite shafts with no issues at all. http://www.golfgalaxy.com/GolfWorks-Graphite-Shaft-Extensions/PAPMACGLFJOIEKCP/Product

They are steel shafts.  I was thinking of using these: http://www.golfworks.com/product.asp_Q_pn_E_WBE60_A_cn_E_2555

Maybe the lighter the better just not sure.

No club repair expert out there?

Calling @WUTiger ..... Not that I doubt Jeff, I just wanted to try the page feature thingy! :-)

A couple of advice points on shaft extensions, courtesy of GolfWorks :

• Don't extend a non-putter shaft more than 1"... possible safety problems.
• It's best to bond like substances to each other. Do not extend a graphite shaft with a steel section. This creates a possible shear point.

For material, you can use the wood inserts, or else extend steel with salvaged steel shaft segments trimmed just below the step points.

As others have said, be aware that every 1/2" of extension increases the swingweight by +3.