Seco Tools India [P] Ltd. Offers Square Shoulder Milling Inserts with Diameter Range 20 to 250 mm. Seco Tools India [P] Ltd is an ISO 9001 and ISO 14001 accredited company. The Square Shoulder Milling Inserts with Diameter Range 20 to 250 mm is used for general purpose square shoulder milling applications. The 12 mm highly-positive inserts allows it to make short work of a wide range of materials and applications.