High quality, Multi - purpose 27.5 lb/12.5 kg bumpers adapt to either pound bars and weight sets or kilo bars and weight sets:

With 45 lb bars, begin with 100 lbs for easy adding:

27.5 lb bumper x 2 plus 45 lbs = 100 lbs

With 15 kg bars begin with 40 kg:

12.5 kg x 2 + 15 kg = 40 kg

Unique design (27.5 lbs = 12.5 kg) simplifies counting and adding weight to two different weight systems.