This upgrade will flatten the cut which should solve the issue of some optics not being able to be zeroed due to the slope of the original optic ready cut. This is for milling of the optic ready M&P Shield Plus version slides ONLY. This upgrade will allow for direct mounting of Holosun 407k/507k/EPS/EPS Carry optics without the use of an adapter plate over the existing optics cut. For NON-Optic Ready M&P Shield Plus milling click here. ***M&P Shield slides that are cerakoted or black nitrided may need to have the striker channel liner replaced. If you send a new channel liner with the slide we will install it before shipping back to you, if a new channel liner is not included with the slide you may need to install one when you receive the slide back. Welcome to the #boomsquad ! Shipping instructions will be provided after your purchase.