Replacement battery fits 5 Righton compatible models. Specifications: 2600mAh, 7.4V, Li-ion. Compatible with: Retinomax 3, K-Plus 3, LUNEAU Retinomax III K+, Retinomax hand auto refractometer series 3, Retinomax hand RT-121. Replaces: Righton RT-121, LUNEAU 88889045, Retinomax hand 1716318. Righton replacement battery designed for Medical devices. Designed for long-lasting power.