When I tried the OEM horizontal clamp down bracket on the Optima battery it just didn't fit. It was too small. Luckily, I was able to use one of the 8 in. bolts (see previous picture) that I bought as a makeshift horizontal clamp. It had a loop at the end that I used for the stock vertical hold down bolt (which was just long enough to reach). Also, the 8 in bolt was long enough to go into bracket that the OEM horizontal clamp down bolt went into.