it's a bottle exchange. you lose your empties and they give you new ones while still moving on your bike. bottles are pretty universal they should fit.

they will give you standard 24 ounce bike water bottles with water unless they state otherwise. the bottles will fit your bottle cage. some folks do dump the contents into their own bottles/aero drink system.

at my 2 IM's and hubby's HIM they give you bottled water or gatorade like you would get at the store, not a bike bottle. So, I start out with the same crappy bottles (with my own mix) and if I need water on the course i can just toss it with out worrying about loosin a good bottle. I also have my aero bottle, so just dump water/gatorade into that and toss theirs.

Suggestion: Start the bike portion with crappy bottles or store-bought bottled water/Gatorade because you will chunk whatever you have when you hit the bottle exchange. Invariably you will see someone who starts with $15 polar bottles who chunks them at hand-up #1 to make room for new bottles. (You may also see this area referred to as 'hand ups'.) As everyone has said, they are usually store-bought water or gatorade bottles - already opened for you - that they hand to you as you ride by. Be careful of other riders and be careful not to run over bottles that have already been missed. Also, the 'hand up' area sometimes have big trashcans painted with targets, or soccer goals so you can have a moment of levity and see if you can hit the trash with a bottle while moving by. Make sure you throw your trashed bottles immediately before or after the hand-up area: this is the only area of a race where you are able to 'litter.' If they race is really crowded I have found it helpful to vocalize what you want as you approach, saying 'gatorade' or 'water' and pointing or calling to a volunteer (nicely, of course). They usually perk right up and make eye contact with you and will pace along side of you for a quicker hand up. Riding by them at speed while they stand still will cause the bottle to drop, so they have to jog next to you or you have to slow way down.

Another addition to Anton's warnings is that may full bottles get dropped in the area. Be on the lookout for bottles laying on the ground as your ride through, you wouldn't want to hit one and end up eating it.

And another bit of aid station etiquette: slow down a bit! Volunteers don't want to lose and arm, and you probably really want that bottle. Sit up, slow a bit, and say thank you! :)

It's funny how hard it is to actually grab ahold of the dang bottle as you ride by. Maybe thats why they call it a bottle "drop".

reviving this older thread -
Do you all find that the bottles you get are usually the sport drink style? I assume we're not talking about screw top bottles right?

The ones I've seen have all had the squirt bottles. I can't imagine they'd make you unscrew a cap on your bike... but there may be some sadistic race director out there. :)
jono