Our 30mm through deck double dynamic block provides smooth and reliable guidance for rope and wire control lines that must pass through a deck. With a durable acetal body and perfectly shaped sheave, this block is ideal for adjustable rigging and other heavily loaded applications. Featuring a patented bearing system with twin rows of stainless steel ball bearings on a stainless steel rail, this block offers superior load-carrying capacity and longevity compared to those with plastic rails.