Modname ckeditor =Specification: Material: Carbon Steel Surface: Black FinishDiameter: 3, 4, 5, 6, 8, 10, 12mm Color: As the picture shows Mainly for fixing the drill bit, limit the depth of the drill holes, make the hole depth consistentMore convenient to use the round wood groovePackage Included:7pcs x Alloy Collars1pc x Hex WrenchNote:Please allow 1-5mm errors due to manual measurementItem color displayed in the pictures may vary slightly showing up on a computer monitor, because self-payment monitors are not calibratedWe support the following payment methods. All payments made on AliExpress are processed by Alipay.Payments1) we accept Alipay, West Union, TT. All major credit cards are accepted through the payment processor's secure escrow.2) payment must be made within 3 days of placing the order.3) if you are unable to check out immediately after the listing ends, please wait a few minutes and try again, payments must be completed within 3 days. Shipping1.