A tamper-evident cover 256 for use with a component comprising first and second portions and an actuator mechanism that moves or allows the first and second portions to move relative to one another, comprises a cover portion 262 defining a cavity which receives the actuator mechanism and prevents access from the exterior of the cover 256. The cover 256 has a retention barb 260 connected to it which is housed within the cavity such that it is inaccessible from the exterior of the cover 256. The retention barb 260 engages with the component so as to retain the cover portion 256 over the actuator mechanism. The component can be a clamp, comprising arcuate portions hingedly connected together, and a ratchet mechanism for locking the arcuate portions in a closed position. The ratchet mechanism comprises a linear rack on one arcuate portion and a pawl on another arcuate portion for receiving the linear rack. The linear rack comprises asymmetrical teeth and the pawl comprises a plurality of fingers which are biased into engagement with the teeth. Another aspect has the clamp comprising a shaft on one arcuate portion, and a cam surface which forces the shaft towards the hinged arcuate portion.
