Good evening,
I tend to call any oval style fitting "Lokfast" Mr RA! So the mount on my 18x12 SS bass seen below sports a "Lokfast" fitting, well to me anyway!
I see your set has hit an evolutionary cusp, you have what is commonly referred to as a "dagger" mount on the bass and 3point spigot plate to the 12, just like the BDP set below. The dagger mount supercedes the original "disappearing" style arm/mount as seen on the White Pearl below which in turn is replaced by what I like to refer to as the "eartrumpet". Quite possibly the single most useless piece of hardware ever produced by Premier in my opinion. Or maybe it is the other way around, can't quite remember!
Either way i'm a 12 in a standman usually so that's all academic really. Occasionally though I can get right heretical (insert evil icon here), witness one of my keeper sets with Yamaha fittings!!
Spart