Rated 4.9 out of 5 by our customers
Rated 4.9 out of 5 by our customers
90 Day Risk Free Returns
Price Match Promise
5 Star Rated by Sailors
Over 70,000+ Orders Shipped
The 20mm block from Allen is the go-to low friction, fast rolling, small pulley in the range and will be seen on a variety of boat sizes.
The Allen 20mm block is Available with a wide range of accessories and features to suit most control line applications.
Explore other Allen block and pulley sizes on our Allen Block page.
Some frequently asked questions that other customers have asked us about Allen 20mm Blocks.
What are Allen 20mm blocks used for?
Allen 20mm blocks are small, low friction blocks used in dinghy control systems. You will find them in kicker and vang cascades, cunningham and downhaul systems, outhauls and other fine tune controls where space and weight matter. They are available as single, double and triple blocks, with becket, fork head, swivel, cheek and stand up versions to suit different fitting points.
What is the difference between Allen dynamic and plain bearing 20mm blocks?
Allen dynamic blocks run on ball bearings, so they spin freely and are the best choice for control ropes that are adjusted often while sailing. Plain bearing blocks use a simpler bearing with no balls, which suits static loads or controls that are set and left. Plain bearing blocks also cost less, making them a sensible option for less critical systems.
What is an Allen Tii-On block?
An Allen Tii-On block is designed to be tied or lashed in place with rope or a soft shackle, instead of being fixed with a metal shackle. The rope passes through the centre of the block, which keeps the system light and lets the block align itself with the load. Tii-On blocks are popular in modern spliced control systems.
Should I choose a standard, High Load or Extreme High Load 20mm block?
Choose a standard Allen 20mm dynamic block for most dinghy control systems. Step up to a High Load version where a small block carries a bigger load, such as the final stages of a kicker cascade. Extreme High Load blocks are built for the most demanding applications on skiffs, catamarans and keelboats, where loads are high but the block must stay compact.
What size rope fits an Allen 20mm block?
Allen 20mm blocks are designed for small diameter control ropes, typically up to 6mm. They work particularly well with 3mm to 5mm Dyneema and polyester control ropes used in dinghy purchase systems. Always check the maximum rope diameter and working load on the individual product page before you buy.
