From their website:
We’ve re-introduced the concrete slabs that we used to use for making our range of Sci-Fi fortifications.
These are now cast in resin, but with all the detail and characters of the original plaster-cast slabs. The pack has 35 slabs in it, each slab roughly 26mm x 14mm x 3mm and around 20+ unique pieces so that repetition is kept to an absolute minimum.
They make ideal pieces for facing fortification for sci-fi games such as Warhammer 40k, Infinity and so forth. Easy to paint – black basecoat, drybrush in some grey, then give them a quick oil/enamel or acrylic wash to bring out the oodles of fine surface detail.
You can find them here, priced at £3.99p per pack.