i have model 639 fieldmate, '86 vintage, took it flyfishing last weekend. at our campsite we needed some small kindling pieces. i fished out the fieldmate(it has a convexed edge) and proceeded to baton it through 12" tall pieces of oak and ash logs. i must have batoned through 20-25 pieces. it was still shaving sharp. the 425m is good stuff i reckon.:thumbup: