All our products are delivered according to the applicable DIN, NEN, or ISO standards. The theoretical calculation of our springs is based on DIN-Taschenbuch 29, Federn 1, and DIN-Taschenbuch 349, Federn 2. 3.1 material certificates are available free of charge from our sales department. Upon request, we can provide measurement reports; for this, we ask a small fee starting from €12.50 depending on the quantity. We provide Certificates of Conformity (COC) upon request; please inquire about options and possible costs.