DISTEL ALU PLUS ARBFICTIONDescription The shafts of the Distel Alu PLUS tree climbing spikes are forged by DMM and ergonomically angled in three planes. The 45 mm wide stirrup is slightly offset forward at an ergonomic angle to the lower leg. This not only makes the Alu PLUS spikes more stable but also particularly comfortable. The Vibram rubber coating provides a firm grip on branches. The comfortable, padded plastic shells are height adjustable on the shaft in 1 4 inch