57mm Zircon Double Block
57mm Zircon Double Block

57mm Zircon Double Block

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Zircon blocks help trimmers match sail shapes to new conditions immediately. At the core of the Zircon performance are industrial ceramic ball bearings mounted inside cages races. The cages keep these bearings separated so they don't bunch, touch, and stop each other. The result is the most efficient small boat block Harken has ever made. 

Sheave Ø (mm) 57 mm
Sheave Ø (in) 2 1/4 in
Length (mm) 79 mm
Length (in) 3 1/8 in
Weight (g) 86.4 g
Weight (oz) 3.05 oz
Maximum line Ø (mm) 10 mm
Maximum line Ø (in) 3/8 in
Maximum working load (kg) 300 kg
Maximum working load (lb) 660 lb
Breaking load (kg) 900 kg
Breaking load (lb) 1980 lb

After ordering online, you will receive an automated email confirmation containing your order details. Your order will then be confirmed within a few minutes of placing your order.

It is our policy to ensure we deliver to our customers in a timely manner. In order to achieve this we use a range of freight companies depending on the size and weight of your order. In some instances we may use a number of carriers to get your products to you. For example, chain may come by road, some electronic equipment by air.


Most orders are shipped within 2 - 5 Days

Shipping rates

Orders delivered to Australian Post Codes attract an $18.00 Flat Rate Shipping Charge* This excludes Bulky or Dangerous Goods


For Bulky Goods, Dangerous Goods and Remote areas.

If the cost to send is vastly different to our standard delivery costs, someone from our team will contact you prior to dispatch to arrange further payment or to issue a refund if you are not happy with the additional charges.

International orders will be charged at $0.00 initially and our staff will be in contact with a shipping quote. If the quote is not accepted the customer reserves the right to cancel their order and be refunded in full.

Should you have any queries or concerns about shipping, please don't hesitate to get in touch by clicking the support button on bottom right of the page.

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