Practice Butterfly Knife with Bonus Credit Card Knife Dull blade for practice, so you wont cut yourself. (Can not be sharpened.) Practice Butterfly Knife Weight: 4.6oz. (good balance and great movement in the joints, which can be tightened.) Quality 440C stainless steel construction with removable screws Bonus Iain Sinclair credit card folding safety knife Practice Butterfly Knife Overall Length: cm (8.6 inches) Blade Length: (3 3/4 inches)