THE JAWS OPEN AND CLOSE TOGETHER. THIS CHUCK WAS PART OF A FIXTURE USED TO MEASURE AUTOMOTIVE BRAKE ROTORS. THE CHUCK WAS SCREWED TO A PLATE AND IT HAS NEVER BEEN TURNED ON A LATHE. THE METAL PIECES ON THE ENDS OF THE JAWS CAN BE REMOVED. THE JAWS OPEN AND CLOSE FINE. THERE ARE MEASUREMENTS IN THE PICTURES. LOOK AT THE PICTURES. CHECK OUT MY OTHER LISTINGS. NO WARRANTIES GIVEN OR IMPLIED. NO EXCEPTIONS; NO MATTER HOW CLOSE YOU THINK YOU LIVE TO MY LOCATION. International Buyers – Please Note. I do not mark merchandise values below value or mark items as “gifts” – US and International government regulations prohibit such behavior.