These are flat-packed Brood/Deep British National frames with gimp pins. They are self spacing and mostly used in British National, WBC and similarly sized beehives.The frames are A grade quality and can be used mixed with DN1 frames if plastic spacers are also used.These are the national brood frames with DN4 top bar. Apis Bee Supplies was started in 2018 on the shores of Lough De... https://www.apisbeesupplies.ie/frames-and-foundation