These are the best size caves for breeding bristlenose plecos. Yes, even longfin bristlenose use these to breed. These are great for em. Many other plecos as well. Not big enough for the common pleco though. 1.5 inch diameter hole. These are fragile and we do expect some to break during shipping from time to time. Please understand we will ship a new one as a replacement and it is the nature of shipping fragile things such as these. We will do everything we can to get them to you intact the first time.