Single Tii-On With High Load Sheave. The stainless-steel sheave runs on a race of stainless-steel ball bearings which results in higher performance and working loads when compared to the standard acetal sheave version. The stainless-steel sheave offers the option of using the block with wire applications, it also stops the deformation of the sheave under high loads. Tii blocks are designed for soft attachment applications. Perfect for use in systems where weight saving is a necessity or there is no requirement for a metal shackle. Allen Tii blocks feature a standout difference from their competition. A stainless-steel ring at the head of the block. The ring is designed to strengthen the block so that any cheek splitting loads are dissipated, allowing for higher working loads when compared to competitors tie on blocks in the same category.