Welcome, and thank you for looking! One single Horolovar 400-Day Clock Temperature Compensating Pendulum Suspension Spring of the thickness of your choice. Each spring thicker than .0040″ – .102mm is 7-1/4″ – 184.2mm long. All others are 5-3/8″ – 136.5mm long. (All springs are longer than you will actually need for your anniversary clock.) Horolovar® Temperature Compensating Springs are made fromNi-Span-C® and are available in 24 different strengths. We can help you find the right springs for your clock, and help you assemble your suspension unit to the proper dimensions. We know anniversary clocks. Any questions, just ask!(Click on one of the Store Categories links to the left to see our instruction booklets, repair books, a full selection of Horolovar suspension spring sizes, complete Horolovar suspension spring units for all Kundo and Schatz clocks, winding keys, mainsprings, and many other anniversary clock related items.) We provide tracking for all shipments within the USA, and to those countries participating in e-DELCON service! And shipping within the USA is FREE!!!NOTE: International purchases do not include import duties, taxes, or charges and are not included in the item price or shipping cost. These charges are the buyers responsibility. Check with your country’s customs office to determine what these additional costs will be prior to buying. We want you to be happy with our products and service. Please contact us if you have any questions or problems. We feel you’ve done your share for a successful transaction once you’ve paid for your purchase. Why should you have to wait until you’ve left positive feedback to the seller before receiving your feedback?We leave positive feedback when payment clears!We will usually ship within 1 business day of receiving cleared payment.