Sorry? I think what you call keepers we would call the collets? The small, tapered retainers that keep the valve spring caps from popping off the valve stem?
By 'Specifics' do you mean what are their precise dimensions? I have no idea to be honest, I've never bothered measuring them. I've had a couple escape but I've always managed to find them again but having had a few blow-ups we have spares. I'd send you one but the cost would be silly.
285846 is their part #