This 300-piece copper metric sealing washers assortment kit is an essential addition to any toolbox, offering 12 different sizes to handle a wide range of fastening and sealing applications. Designed for use with oil drain plugs, hydraulic fittings, and pipe connections, these solid copper flat washers provide a reliable, leak-resistant seal every time. The kit includes sizes ranging from M5x9x1.0mm up to M20x26x1.5mm, ensuring you always have the right washer on hand for the job. Each washer is crafted from solid copper, known for its excellent malleability and ability to conform tightly under compression, creating a dependable seal. All 300 pieces are neatly organized in a reusable plastic storage case with individual compartments, making it easy to sort and locate the exact size you need. Whether you are a professional mechanic or a dedicated DIY enthusiast, this comprehensive assortment kit is a practical solution for keeping your plumbing and mechanical connections tight and secure. Not suitable for children under 6 years of age due to small parts.