Compression fittings are very versatile, but many people are not confident when using them. Some people also believe that you need to use a sealing compound or PTFE tape with compression fittings, but simply is not the case (unless your compression fitting is leaking). Once the olive has been compressed sufficiently the joint should be a quick and leak free fitting for life. I do prefer copper olives to brass olives as they are easier to compress. Compression fittings are versatile and can be used on copper pipe or plastic pipe with a pipe insert.