BP1 900 x 700 x 450mm, 225 litre capacity bund, one 205 litre drum BP2 1220 x 820 x 330mm, 240 litre capacity bund, two 205 litre drums BP4 BP4 1310 x 1310 x 370mm, 410 litre capacity bund, four 205 litre drums BP4L 1280 x 1280 x 275mm, 230 litre capacity bund, four 205 litre drums (BP4L is a low height unit) BP8 2560 x 1350 x 510mm, 1140 litre capacity bund, eight 205 litre drums. BP4C self assembly frame and cover only for use with BP4 BB2C self assembly frame and cover only for use with BP8 or BB2