Other radio advertising, especially when produced by a local radio station, is more straightforward, with a recognizable disk jockey or business owner providing the voice-over. Depending on the size of the radio station and the client's budget, on-air talent may be responsible for the production of radio advertising or it may be farmed out to a professional advertising agency to achieve the client's vision. Because radio station managers have a limited number of minutes available for advertising during an average hour, radio spots tend to last either 30 or 60 seconds. A station may build in several scheduled breaks during an hour, typically at twenty minutes or so after the top of the hour and twenty minutes before the top of the next hour. If there is enough radio advertising spots available, additional breaks at ten minutes before the hour and ten minutes after the hours may be added. Each break may have two to three minutes allotted for spots, which can be introduced with a station jingle or a longer promotion called a sweep. Advertisers generally pay for the number of times a particular radio spot is played, or "dropped" in radio lingo. A radio ad dropped primarily during the overnight hours may be less expensive than a similar ad dropped during the popular morning or afternoon drive times. Radio advertising, especially for a popular station with a powerful transmitter, can be a considerable expense up front, but the number of potential listeners within range of the station is often exponentially higher than subscribers to local newspapers or regular viewers of local television stations.