These jewelry crimp end pieces with loop work well with small-diameter cording and cable.
The 0.8mm I.D. (inner diameter) styles work perfectly with 0.8mm beading chain.
Crimp ends with loops are designed to be flattened. (Do not attempt to round them after flattening, like you would with crimp beads and crimping pliers.) Depending on their size (length) and your personal preferences, you can flatten them with round-nose pliers or chain-nose pliers (smooth flat-nose pliers).