I have placed primary and permanent Stainless Steel Crowns since 1974. Unitek Stainless Steel crowns had no contours to them. Everything had to be crimped. When the 3M Pre-trimmed and crimped crown was available I started using them. I now use the KTR Nichro Pre-trimmed and crimped crowns. The crowns are anatomically formed and cost effective. When you purchase the introductory 48 Crown KTR Nichro kit the container box they come in is superb. When the box is moved or turned upside down the crowns stay in each location.