I know the OP specified 5C & I have what I suspect are the same Chinese blocks shown. And yes, they are a bit of a knuckle skinner to tighten/loosen properly & the cam handle thing is never in a good setup spot.
But also mentioning if you happen to have ER collets or considering them, these blocks are available & serve the same function. But the rings are easier to tighten IMO & smaller ER's make for smaller setups if that's an issue. I bought the ER40 blocks, shipping was reasonable & speedy. They look to be every bit as good or maybe a tad nicer than the 5C blocks. Unfortunately I couldn't find any N-Am suppliers of this which is odd. One would think they would be everywhere. Maybe they have their own gig?
http://www.arceurotrade.co.uk/catalogue/results.aspx?search=collet+block
But also mentioning if you happen to have ER collets or considering them, these blocks are available & serve the same function. But the rings are easier to tighten IMO & smaller ER's make for smaller setups if that's an issue. I bought the ER40 blocks, shipping was reasonable & speedy. They look to be every bit as good or maybe a tad nicer than the 5C blocks. Unfortunately I couldn't find any N-Am suppliers of this which is odd. One would think they would be everywhere. Maybe they have their own gig?
http://www.arceurotrade.co.uk/catalogue/results.aspx?search=collet+block