Hi Michelleesh, I'm not clear if you mean the 3 column itself or the bottle slots. The slots will fit Pinot Noir and Turly bottles (although the slightly bigger ones may 'rest' on other bottles when sitting) and those bottles can go up to 3 9/16". As it's a holiday weekend I don't have the exact measurements at this time. Be sure and contact us directly if you need specifications so we can email the assembly manuals to you. Thanks! - KD

Thanks KD for the quick response! I am hoping to fit custom bottles with a 3.5" diameter. It sounds like based on what you said that these will be wide enough? Does it get unstable at all when the bottles are 'resting' on other bottles? Thanks again! :)

It should be fine. It's not unstable because the racks should be bracketed to the wall. The bottles will just rest upon each other if they are slightly larger. You may wish to compare our WineMaker line to the Vintner series. Same type of racking but Vintner is full depth which holds the full body of the bottle and has a little bit more room for the bottles. WineMaker is short depth, still holds the majority of the bottle but the necks stick out a bit. I sometimes prefer WineMaker especially with a display row because it pops out the bottle and makes it a showcase. You can see our Photo Galleries here in Houzz for more exampes. Also, WMK is more affordable because it uses less wood. But definitely check out both!

WMK: http://www.houzz.com/projects/512531/winemaker-series-wine-racks-customer-photos

VNT: http://www.houzz.com/projects/546323/vintner-series-wine-racks-customer-photos

You can see how people use it with or without moldings, different woods and stains, etc. Let us know if you need a free design. - KD