The most popular Type of screw down for Trading cards on the market today. This new and improved version has recessed Arrowhead in each corner so that the Trading card's corners are never touched. It also has a white frost on all four sides of the card which makes the collectible card stand out better. Invented by pro-mold in 1993. Strengths: small and compact compared to traditional style four screw screwdowns which allows for storage of many in smaller spaces particularly in MONSTER boxes or shoe boxes. What made the one screw screw down popular is the fact that you get all the benefits of a four screw, as far as protection of the Trading card goes, but with only having to use one screw instead of four. Weaknesses: this baseball card case itself has no real weakness but some collector's prefer not to deal with screw down holders because they're time consuming and tedious to screw together many at a time, which is why they use the snap-design holders instead. Fits bowman baseball cards from 1948, 1949, and 1950