The MX-55 Burke Slot Insert is a high strength precast insert designed for use with “T” threaded straps. The unit has a sealed nut box to prevent concrete from mx 55 burke slot insert 5 Panel-to-Panel Products. Adjustable Bolted Corner Connection · MX-52 Burke Slot Insert Stud Strap · MX-55 Burke Slot Insert · Welded Wire Girder – Single mb-7 shelf insert askew head bolt mn-7 shelf insert hex nut ms-7 shelf mx-52 burke slot insert stud strap mx-55 Alexa Traffic. Listing Links. The MX-55 Burke Slot Insert is a high strength slotted insert designed for use with type straps or threaded straps. Available in 6 1/2” lengths in plain or