Bolt-in counterweights are a major plus feature in all of our externally balanced dampers. For example, if you purchased one of our externally balanced dampers and during your engine build procedure, you decided you want to switch to a neutral balance assembly; you don"t need to buy a new damper. You simply unbolt the counterweight and you are good to go. Some of our competitors who lack this feature have made claims in some of their literature that bolt-in counterweights are a bad thing because they can "come loose" or "fall out" and "do serious damage." Professional balance shops really like this feature because if they need to modify the counterbalance weight for any reason, it is much easier to do this with a removable counterweight than to try to remove weight from the damper itself.