4V LiPo 2S Size: 36 x 28 x 16 mm Weight: 38g Manual: ENGLISH ONLY

You can see which battery pack Traxxas recommends for your vehicle here:

F949-5 Landings-hjul - reservedel til F949 fjernstyret fly

Specially made just for polycarbonate

Same size as:

Batteri AAA (4 stk.) Hammer 4V LiPo 2S Size: 36GP Super Alkaline 4 pcs. AAA alkaline batteries with high performance, perfect for your radio transmitter! These batteries strike a great balance between high output and performance. You'll get the best performance in your RC control by using alkaline batteries instead of rechargeables. Alkaline batteries offer higher output (1. 5V vs. 1. 2V) and maintain power longer.