The articulating ankle joint comes with a plantar flexion stop made of an elastic bumper.  It can be ordered in titanium, aluminum, or stainless steel.     

This adapter is to be used with the Single Axis Foot

Stainless Steel Adapter - Small
Foot Size:  22cm - 25cm 
Weight Limit:  220lbs (100kg)
Unit Weight:  10.76 ounces (305g)

Stainless Steel Adapter - Large
Foot Size:  26cm - 30cm 
Weight Limit:  220lbs (100kg)
Unit Weight:  11.18 ounces (317g)

Aluminum Adapter - Small
Foot Size:  22cm - 25cm
Weight Limit:  198lbs (90kg)
Unit Weight:  7.87 ounces (223g)

Aluminum Adapter - Large
Foot Size:  26cm - 30cm
Weight Limit:  198lbs (90kg)
Unit Weight:  8.01 ounces (227g)

Titanium Adapter - Small
Foot Size:  22cm - 25cm
Weight Limit:  220lbs (100kg)
Unit Weight:  6.95 ounces (197g)

Titanium Adapter - Large
Foot Size:  26cm - 30cm
Weight Limit:  220lbs (100kg)
Unit Weight:  7.16 ounces (203g)