Grade 6061-T6 aluminum with compound filled grooves. For inclined ladder. Cap treads are typically installed atop Type CTFT treads and do not have end plates. Countersunk mounting screw holes drilled in the surface. Fits over tread measuring 4"W x 1-3/4"H. MIL-T-24634 Type II. Please specify overall length (treads will be supplied 1/8" shorter to ensure fit between the ladder stringers). Ships in 8-10 weeks after receipt of order.