The cast aluminum arb pulleys from ISC are probably the most widely used arborist rigging blocks in the world. Developed back in 1996 the ISC blocks have remained virtually unchanged since their inception 15 years ago - tried and true it seems.
But times change and ISC recognized the need for an update. The new (improved) ISC blocks were introduced the market at the TCI Expo in the US back in
November 2010 but will not be officially launched until June in the UK.
ISC have rounded the edges somewhat (although not to the same degree as the competitor product from DMM and the Treemagineers). The pulley certification details are now located on an aluminum plate riveted below the spindle.
The hole for the top internal spring lock has its edges honed nicely to improve pin location and the overall width of the block has been increased by 35% to accommodate larger diameter ropes. The spindle diameter, top and bottom, has 10% more meat to handle the extra load.
Cynics will say the 'improvements' are cosmetic and they may well be right, but there is no doubt about the popularity of these ISC blocks regardless of their better looks - they sell 10:1 the volume of anything else in the market!
The 'classic' ISC block is shown on the left in B&W for comparison. Don't expect to see the 'improved' ISC blocks in New Zealand until later in the year!