Allen 20mm Dynamic Back to Back Block

Two 20mm dynamic sheaves set opposing each other and on the same plane, both have hollow axles for use as a tie on becket. The block will work with up to 6mm line but the becket will only take up to 4mm line.

Often used in asymmetric spinnaker halyard systems to launch the pole at the same time as the spinnaker

To fully appreciate the difference of the Allen dynamic bearing range of blocks, take a closer look at the design, quality of materials and construction to fully appreciate the difference. From the patented high strength 316 stainless steel line friendly ultra strap, to the soft contours of the sheave and cheeks moulded from advanced engineering polymers, patented dynamic bearing technology featuring twin rows of 316 stainless steel ball bearings all held together with a meticulously designed 316 stainless steel jacket, Allen blocks claim to be the strongest and best available on the market.