Sale HO scale Walthers HO Walthers Proto MAX HO 920-6000 Magnetic Knuckle Couplers Standard Type - 20 Pair Walthers Proto MAX HO 920-6000 Magnetic Knuckle Couplers Standard Type - 20 Pair Walthers Proto MAX couplers are an easy upgrade for old or new equipment and provide magnetic uncoupling action. Fully assembled, they fit most HO equipment, and each... $31.98 $25.99 Add to Cart Add to Wish list Compare