There is no perfect way to prove that any safety needle technology works to reduce needlesticks. The old standby, controlled clinical trials against a placebo or (in this case) a standard needle, would raise legal and safety questions. The next best thing is using an historical control. (e.g. we used standard needles during the period Y, now we have used safety product for the same length of time. ) Then, compare rates of needlesticks, perhaps using statistics to account for other important variables such as training, use restrictions, workload, etc. How many such studies have you seen published in reputable journals, for any of these products? If a manufacturer/seller has hard data, lets see a few references. Until then, I'm using a whole salt shaker, not just a grain.