Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| Race | Length | Class | Circuit | Date |
| --- | --- | --- | --- | --- |
| 24 Hours of Daytona | 24 Hours | All | Daytona International Speedway | February 4 February 5 |
| 12 Hours of Sebring | 12 Hours | All | Sebring International Raceway | March 18 |
| 6 Hours of Talladega | 6 Hours | All | Talladega Superspeedway | April 2 |
| Camel GT Challenge | mi (km) | GTU | Road Atlanta | April 16 |
| Camel GT Challenge | mi (km) | GTX/GTO | Road Atlanta | April 16 |
| Monterey Triple Crown | mi (km) | GTX/GTO | Laguna Seca Raceway | April 30 |
| Monterey Triple Crown | 45 Minutes | GTU | Laguna Seca Raceway | April 30 |
| Hallett Grand Prix | 1 Hour | GTU | Hallett Motor Racing Circuit | May 7 |
| Hallett Grand Prix | mi (km) | GTX/GTO | Hallett Motor Racing Circuit | May 7 |
| Coca-Cola 300 | mi (km) | GTX/GTO | Lime Rock Park | May 29 |
| Coca-Cola 300 | mi (km) | GTU | Lime Rock Park | May 29 |
| Pepsi Grand Prix | mi (km) | All | Brainerd International Raceway | June 18 |
| Paul Revere 250 | mi (km) | All | Daytona International Speedway | July 4 |
| Sears Point Grand Prix | mi (km) | GTX/GTO | Sears Point International Raceway | July 30 |
| Sears Point Grand Prix | mi (km) | GTU | Sears Point International Raceway | July 30 |
| G.I. Joe's Grand Prix | mi (km) | GTX/GTO | Portland International Raceway | August 6 |
| G.I. Joe's Grand Prix | 45 Minutes | GTU | Portland International Raceway | August 6 |
| Camel GT Mid-Ohio 250 | mi (km) | All | Mid-Ohio Sports Car Course | August 27 |
| Arthur Montgomery 100 | mi (km) | GTU | Road Atlanta | September 4 |
| Arthur Montgomery 100 | mi (km) | GTX/GTO | Road Atlanta | September 4 |
| Camel GT Daytona 250 | mi (km) | All | Daytona International Speedway | November 26 |
Question:
Which circuit was held on May 7 for 1 hour?
Answer:
Hallett Motor Racing Circuit