The Carhartt R01 Duck Double Knee Overall Bibs are well-known for their exceptional quality and durability. If you have a vintage pair that is new with tags and was made in America in the 90s, you likely have a highly sought-after item. Here are some details about their quality:

1. Construction: Carhartt is renowned for its sturdy construction techniques. The R01 Duck Double Knee Overall Bibs are made from heavyweight cotton duck fabric, which is known for its durability and resistance to abrasion. The double knees provide extra reinforcement in a high-wear area, ensuring longevity.

2. Stitching: Carhartt takes pride in its reinforced stitching, which enhances the overall strength of the bibs. This attention to detail minimizes the risk of seam failure, making the bibs more resistant to wear and tear.

3. Functionality: These bibs are designed with functionality in mind. They feature multiple pockets, such as a bib pocket, utility pockets, and reinforced back pockets, offering ample storage space for tools and personal items. The adjustable shoulder straps allow for a customized fit, ensuring comfort during extended wear.

4. Made in USA: Carhartt's products made in America are often associated with superior craftsmanship. The fact that your bibs were made in the USA adds to their quality and authenticity.

5. Vintage Appeal: Vintage Carhartt items are highly sought after by enthusiasts and collectors due to their timeless style and reputation for durability. The fact that your bibs are new with tags suggests that they have been well-preserved, maintaining their original condition and possibly increasing their value.

Overall, the Carhartt R01 Duck Double Knee Overall Bibs made in the USA in the 90s are likely to be of exceptional quality. The combination of their vintage nature, new condition, and American production further enhances their desirability among Carhartt enthusiasts and those seeking reliable workwear.