All top tube bags fit a top tube with a circumference up to 18cm (7"), which is suitable for every stock road or gravel bikes. If you using a tandem, recumbent or some dual-tube mountain bikes, with larger than typical top tube, then purchase our optional #2446 Top Tube Bag Extender Straps. *** Warnings: 1) Some cyclists do not like having a bag on the top tube as it may interfere with their knees, esp. while standing up to pedal. 2) We have had isolated reports of paint rubbing off caused from bottom fabric on this bag. You may want to pre-tape your top tube first with electrical, helicopter or protectant clear tape. *** SPECIFICATIONS FOR MEDIUM: The maximum size phone, including the case, that will fit is up to 160mm long x 80mm wide (6-1/4 x 3-1/8"). iPhone (non-mini) X, 12, 13, 14, 15 etc. will NOT fit inside this case. Slightly wider phones may fit but only when titled at a slight angle.*** Weight: 87 g (3.1 oz.) Vol: 850 mL (52 cu in)--Inside Dimensions (bottom): 10.5h x 18.5w x 4.4d cm (3.9h x 7.3w x 1.75d") *** SPECIFICATIONS FOR LARGE: The maximum size phone, including the case, that will fit is up to 168 x 87mm (6-5/8 x 3-3/8") such as: iPhone X, 11, 12, 13, 14, 15 etc. (no Max) with a slim-sized case. Samsung Galaxy S, 3, 4 or S5 with a “slim-sized” case. A slim-sized case is one that adds 6 to 9mm. If you need a larger bag, choose the eoGEAR X-Large Century Bag instead (SKU # 2008).