I'm not keen on roller type alarms on the river. They work really well in conjunction with bobbins or a similar indicator, but can be a little hit and miss without. I've had a few sharp rattles and pulls on rod tips that have taken no line and produced no indication from roller type alarms. I prefer the vibration sensing and lack of roller of the Delkim alarms for river fishing.
Many of them are, and have been for quite a few years. The snag is that the alarms, with receivers that have such a feature are generally fairly expensive.
