filled with translucent black water beads. I think it looks a lot better with these in than just an empty bottle with led's in it. it helps to spread the colour through the bottle and it looks nice when the lights are off as well. I send them fully made up but also include an extra bag of ungrown water beads to replace any that get damaged in transit. they can break up and turn to mush if they get shaken around too much so just pour any out that end up like that and replace with the ungrown ones. put them in a bowl of a litre or so of water for at least 12 hours until they have expanded to size. the led's are waterproof and are not a problem to use with the watery environment. have been using these for over a year now with no problems

if exposed to air for prolonged lengths the water beads will end up shrinking in size and can eventually revert to their original size. I have found keeping the bottle cap on stops air getting in and keeps them the same size. there is a small gap where air can get in on the back where the hole is drilled for the led's to go in but it is far less of a problem. they do slowly shrink over time and occasionally I have to top up the bottles with new ones but they last long enough like this. you can also regrow existing ones by putting them back into water again. some may split but I tend to supply enough extra ungrown beads to account for any issues. can require some minor upkeep, water can accumulate in the bottom which can just need emptied out from time to time. generally they're fine to just leave for awhile 

I will combine postage if you buy more than one

Payment to be received within 48 hours of listing end

I leave feedback once received from buyer