I have been looking for some of these weights for awhile now. I first located the MIR brand, but struggled paying more than I wanted to. So, I continued my search and landed on the IRUN, which cost less than MIR, and when I received them and inspected, determined these were exactly what I was looking for. I’m pleased with the product and the delivery. The vendor packaged the 6 that I procured carefully and with pride. I would recommend this product and vendor.My 20lb weight vest wasn't cutting it anymore (has 24 0.8lb sandbags). I purchased the IRun cast-iron weights (10 pack) to bump it to 40 lbs. They fit into the vest nicely and it works. The only issue I have is the weights ranged from 2.71 to 2.92 lbs (using a calibrated scientific scale). In total, the weight was 27.9 lbs. I know there was no claim of calibrated to 3.0 lbs, but I wish 3.0 lbs would have been the average (vs. none even hitting 3.0 lbs).Yes these will fit in your MiR vest and are identical to the 3lb weights that come with a mir vest. I bought a 40lb and wanted to up it to 60lb. Luckily MiR ships an extra weight, perfect combo with this sellers 3 piece offering. Shipping was super fast and the package was more than adequately secured.Fits perfect in my MIR PRO Weighted Vest.I bought these to add more weight to i-run vest that was marketed as being adjustable to add more weight...it wasn't and these didn't fit anyway. Very disappointed, I wouldn't have bought either had I known. Returning weightsthis fit perfectly in my vest.