This Thermo Scientific® ELED test tube block holds 12 to 13mm test tubes. This block is made of anodized aluminum for the greatest heat transfer and retention. For use with the digital 2000 series and analog 2050 series modular block dry baths. Designed to provide close contact of tubes to block walls for excellent heat transfer. Includes thermometer well for monitoring block temperatures, block puller for safe, easy block removal. Dimensions (L x W x H): 3.75 x 2 x 2.9in. No. of Wells: 22. Tube Diameter: 1.35cm (0.53in). Tube Capacity: 12 to 13mm. Thermo Scientific® ELED #: 2072Q. Thermo Scientific ELED - “Every Lab, Every Day”.